Prospects of hybrid renewable energy-based power system: A case study, post analysis of Chipendeke Micro-Hydro, Zimbabwe

Fossil fuel-based energy sources are the major contributors to greenhouse gas (GHG) emission and thus the use of renewable energy (RE) is becoming the best alternative to cater for the increasing energy demand in both developing and developed nations. Chipendeke is a rural community in Zimbabwe, in which electricity demand is partially served by the only micro-hydro plant and hence, load shedding is a regular practice to keep essential services running. This study explored a suitable opportunity to identify a feasible system with different energy sources that can fulfill the current and projected future load demand of the community. A techno-economic feasibility study for a hybrid RE based power system (REPS) is examined considering various energy sources and cost functions. Six different system configurations have been designed with different sizing combinations to identify the most optimum solution for the locality considering techno-economic and environmental viability. The performance metrics considered to evaluate the best suitable model are; Net Present Cost (NPC), Cost of Energy (COE), Renewable Fraction (RF), excess energy and seasonal load variations. In-depth, sensitivity analyses have been performed to investigate the variations of the studied models with a little variation of input variables. Of the studied configurations, an off-grid hybrid Hydro/PV/DG/Battery system was found to be the most economically feasible compared to other configurations. This system had the lowest NPC and COE of $307,657 and$ 0.165/kWh respectively and the highest RF of 87.5%. The proposed hybrid system could apply to any other remote areas in the region and anywhere worldwide

Particle image velocimetry study of a cloud-like flow

This study employs particle image velocimetry (PIV)13; on a jet with and without subjection to internal heating.13; The effects of buoyancy enhancement on the13; entrainment coefficient and on the streamline structures13; responsible for it are investigated. PIV results13; for the unheated jet are in good agreement with earlier13; studies. It is shown that when internal heating is13; present in the flow, the mean entrainment coefficient13; decreases from a value of 0.057 characterizing a standard13; jet to 0.017, at a heating rate of 1400 W corresponding13; to a Richardson number of 0.24. It is also13; shown that the mingling of the entrained fluid with13; the main flow is different in heated and unheated jets

Turbulence and noise suppression of a high-speed jet by water injection

An experimental investigation has been carried out on a supersonic jet of air issuing from an M =1.44 convergingx2013;diverging rectangular nozzle of aspect ratio 4. Particle13; image velocimetry measurements of the flow field along with near-field acoustic measurements were made. The effect of injection of a small amount of water (x223C;5% of the mass flow rate of the jet) into the shear layer of the jet, on the unsteady flow structure and sound generation were examined. The presence of water droplets in the jet modified the turbulence structure significantly, resulting in axial and normal r.m.s.velocity reductions of about 10% and 30%, respectively, as compared to that of a13; normal jet. An even larger effect is found on the peak values of the turbulent shear stress with a reduction of up to 40%. The near-field noise levels (OASPL) were found13; to reduce by about 2x2013;6 dB depending on the location of the injection and the water mass flow rate. Far-field acoustic measurements carried out on a heated M =0.9 (jet13; exit velocity=525msx2212;1) jet show significant (6 dB) reductions in the OASPL with moderate amounts of water injection (17% of the mass flow rate of the jet) suggesting13; that the technique is viable at realistic engine operating conditions

Forecasting of COVID-19 cases using deep learning models: Is it reliable and practically significant?

The ongoing outbreak of the COVID-19 pandemic prevails as an ultimatum to the global economic growth and henceforth, all of society since neither a curing drug nor a preventing vaccine is discovered. The spread of COVID-19 is increasing day by day, imposing human lives and economy at risk. Due to the increased enormity of the number of COVID-19 cases, the role of Artificial Intelligence (AI) is imperative in the current scenario. AI would be a powerful tool to fight against this pandemic outbreak by predicting the number of cases in advance. Deep learning-based time series techniques are considered to predict world-wide COVID-19 cases in advance for short-term and medium-term dependencies with adaptive learning. Initially, the data pre-processing and feature extraction is made with the real world COVID-19 dataset. Subsequently, the prediction of cumulative confirmed, death and recovered global cases are modelled with Auto-Regressive Integrated Moving Average (ARIMA), Long Short-Term Memory (LSTM), Stacked Long Short-Term Memory (SLSTM) and Prophet approaches. For long-term forecasting of COVID-19 cases, multivariate LSTM models is employed. The performance metrics are computed for all the models and the prediction results are subjected to comparative analysis to identify the most reliable model. From the results, it is evident that the Stacked LSTM algorithm yields higher accuracy with an error of less than 2% as compared to the other considered algorithms for the studied performance metrics. Country-specific analysis and city-specific analysis of COVID-19 cases for India and Chennai, respectively, are predicted and analyzed in detail. Also, statistical hypothesis analysis and correlation analysis are done on the COVID-19 datasets by including the features like temperature, rainfall, population, total infected cases, area and population density during the months of May, June, July and August to find out the best suitable model. Further, practical significance of predicting COVID-19 cases is elucidated in terms of assessing pandemic characteristics, scenario planning, optimization of models and supporting Sustainable Development Goals (SDGs)

An experimental study of a jet with local buoyancy enhancement

We report here an experimental study of the behaviour of a fully developed axisymmetric turbulent jet whose buoyancy is enhanced by volumetric heating over the region between two streamwise stations. The buoyancy enhancement is achieved by ohmic heating of an electrically conducting liquid jet, and the measurements are made using a laser Doppler velocimeter. It is found that, with heating, the axial component of mean velocity can increase appreciably relative to the unheated jet; however the turbulent intensity (normalized by the jet centreline velocity) decreases. The shape of the normalized mean velocity distribution across the jet is not significantly affected by the heating, but that of the fluctuating velocity is. The decay of the centreline velocity is considerably slowed down, or even reversed, due to the heating; similarly the spread rate is arrested at larger values of the Richardson number. As a result of the enhanced buoyancy the mass flux in the jet at first increases more rapidly than in the unheated jet but further downstream remains nearly constant over a distance of the order of the length of the heat injection region

Supersonic jet noise suppression by water injection 13;

An experimental investigation was carried out on a supersonic jet of air issuing from an M = 1.44 converging-diverging rectangular nozzle of aspect ratio 4. Particle Image Velocimetry measurements of the flow field, along with acoustic measurements, were obtained. The effects of a small amount of water (about 5 percent of the mass flow rate of the jet), injected into the shear layers of the jet, on the unsteady flow structure and sound generation were examined. The presence of the water droplets in the jet modified the turbulence structure significantly, resulting in rms velocity reductions greater than 30 percent as compared to those of a normal jet. Similar reductions of the forcing term of the Phillip's equation, which represents the generation of the pressure fluctuations in the jet, were also found. The changes observed in the near-field noise measurements, due to water injection, are consistent with the unsteady flow modifications. (Author) 13; 13