Vol. 2 No. 3 (2024)

  • Open Access

    Article

    Article ID: 1431

    Performance evaluation of dewatering systems for bio-digestate for developing countries

    by Ajay Kumar Jha, Sujan Jojiju, Hari Darlami, Bijay Basnet

    Energy Storage and Conversion, Vol.2, No.3, 2024; 5622 Views, 4252 PDF Downloads

    The performance evaluation of a screw type dewatering system for bio-digestate in Nepal demonstrates significant potential for improving the usability and efficiency of bio-digestate as a fertilizer. Remarkable modifications in the previous include a 5 HP motor running at 1440 RPM with a gear reduction ratio of 1:40, a spring assembly system at the outlet, and a fine sieve. Testing and performance analysis at different operating speeds using a variable frequency drive revealed an optimal performance at 8 RPM, where the system achieved a liquid yield of 92.02% and an extraction efficiency of 73.12%. The installation cost of the machine was NPR 384,000, with a payback period of 2 years, six months, and two days. The internal rate of return (IRR) was calculated at 28.53%, while the net present value (NPV) was NPR 179,006.35. This study indicates that operating the dewatering system at lower speeds may improve efficiency and effectiveness in the dewatering process. This makes the machine a viable option for producing organic fertilizer and addressing Nepal’s significant need for fertilizer.

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  • Open Access

    Article

    Article ID: 1515

    Optimal micro-pump-storage system for the average Greek hotel with PV generation

    by Dimitrios K. Kosmopoulos, Admitos A. Bideris-Davos, Panagis N. Vovos

    Energy Storage and Conversion, Vol.2, No.3, 2024; 1019 Views, 908 PDF Downloads

    In this paper, a modern micro-scale pumped hydro storage system that is specifically designed to operate in coordination with photovoltaics installed at the roof of an average Greek hotel is presented. The fictitious hotel chosen as a case study, displays the energy profile of an average sea-side hotel around the Mediterranean Sea, while photovoltaics’ energy generation is assumed to follow the typical production profile of such sites. Pumped hydro storage and photovoltaic generation, size and cost have been appropriately modeled so that they realistically simulate their operational scheme, while also considering the spatial and technical characteristics and limitations of such projects. Results derived from the implementation of such a scheme into the Average Greek hotel demonstrated significant monetary benefits, accompanied with a substantial net annual profit and low payback period of the investment.

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  • Open Access

    Article

    Article ID: 515

    Heat transfer characteristics in Williamson fluid flow in a vertical channel with chemical reaction and entropy production

    by Amala Olkha, Mukesh Kumar

    Energy Storage and Conversion, Vol.2, No.3, 2024; 1585 Views, 1352 PDF Downloads

    This research endeavor investigates the natural convection flow of Williamson fluid in the region between two vertical parallel flat plates via a porous medium. Impacts of viscous dissipation, joule heating, exponential space, and thermal-dependent heat sources (ESHS/THS) are invoked. Mass transfer is also studied in accounting for chemical reaction impact. The governing non-linear PDEs are reduced to ODEs in non-dimensional form under adequate transformation relations. The numerical technique, namely, Runge-Kutta fourth-order, is utilized to tackle the problem with the shooting method. Additionally, second-law analysis is presented in terms of entropy production. The effects of numerous regulating parameters occurred in the problem relevant to flow, heat and mass transport, and entropy production are discussed via graphical mode of representation. Moreover, the quantities of physical significance are computed, displayed in graphical form, and discussed. For verification of acquired results, a comparison is also made using HPM with prior research, which was found to be in excellent agreement. It is concluded that the fluid temperature field enhances with upsurging values of pertinent parameters. The influence of the convective surface parameter and order of reaction are found to make augmentation in mass diffusion. Further, the effect of joule heating is noticed to increase the rate of heat transfer, while the reverse scenario is observed with upsurging values of heat source parameters. The influence of viscous dissipation is seen to increase entropy production.

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  • Open Access

    Review

    Article ID: 538

    Wind power forecasting technologies: A review

    by Krishan Kumar, Priti Prabhakar, Avnesh Verma

    Energy Storage and Conversion, Vol.2, No.3, 2024; 977 Views, 753 PDF Downloads

    This study addresses the critical role of wind power forecasting in ensuring stable and reliable power system operations. Wind power forecasting is critical for the efficient operation of plants, time scheduling, and the balancing of power generation with grid integration systems. Due to its dependency on dynamic climatic conditions and associated factors, accurate wind power forecasting is challenging. The research delves into various aspects, including input data, input selection techniques, data pre-processing, and forecasting methods, with the aim of motivating researchers to design highly efficient online/offline models on weather-based data. The overarching goal is to enhance the reliability and stability of power systems while optimizing energy resource utilization. The analysis reveals that hybrid models offer more accurate results, highlighting their significance in the current era. This study investigates different Wind Power Forecasting (WPF) models from existing literature, focusing on input variables, time horizons, climatic conditions, pre-processing techniques, and sample sizes that affect model accuracy. It covers statistical models like ARMA and ARIMA, along with AI techniques including Deep Learning (DL), Machine Learning (ML), and neural networks, to estimate wind power.

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  • Open Access

    Review

    Article ID: 480

    A Mini Review on Electroosmotic Phenomena in Porous Media

    by Yan Gao, Chunling Wang, Zhuo Gong, Zhiqiang Li

    Energy Storage and Conversion, Vol.2, No.3, 2024; 340 Views, 14 PDF Downloads

    The electroosmosis phenomenon in porous media finds widespread applications in various fields such as microfluidic systems, polymer electrolyte membrane fuel cells, oil and gas engineering, wastewater sludge dewatering, groundwater dynamics, etc. Therefore, the electroosmotic flow mechanism in porous media has attracted broad interest from multiple disciplines. This paper provides an overview of the physical mechanisms and mathematical models for electroosmosis in porous media. The background of electric double layer theory and state-of-the-art research progress on pore-scale models for electroosmotic flow through porous media are reviewed. Two typical and significant research topics, electroosmosis under pressure coupling effects and nanoscale electroosmotic phenomena, are then focused on. The advances in theoretical analysis, numerical simulation, and experimental measurements are summarized. Finally, the potential research directions for electroosmotic flow in porous media are addressed.

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