Cover

Aims and Scope
Editorial Board

1. Experimental and CFD study on the dynamic thermal management in smartphone and using graphene nanosheets coating as an effective cooling technique

Maher A.R. Sadiq Al-Baghdadi ^1,2

¹ Kufa Centre for Advanced Simulation in Engineering (KCASE), Department of Mechanical Engineering, Faculty of Engineering, University of Kufa, Iraq.

² Computational Fluid Dynamics Center, International Energy and Environment Foundation (IEEF), Iraq.

Abstract: Thermal management is essential in electronics, as it improves reliability and enhances performance by removing heat generated by the devices. Maintaining safe chip and device skin temperatures in small form-factor mobile devices (such as smartphones) while continuing to add new functionalities and provide higher performance has emerged as a key challenge. A significant increase in reliability and smartphones life can be achieved by a small reduction in operating temperature. With the limitations of space and power, radiation and natural convection plays an important role in heat removal mechanisms in smartphones engineering designs. A case study on an iPhon5 using CFD is provided to relate the device performance to the skin temperature and investigate the thermal path design. Three dimensional CFD model of an iPhone5 has been presented. The model accounts for heat transfer for conduction through the phone components materials and for both natural convection and radiation to the ambient air temperature. The comparison between the CFD simulation and the thermal image obtained by the thermal camera shows some similarities like, for example, hot-spots located in the same places. The present CFD study allow accurate, rapid, physical modelling to make decisions on materials, components and layout beside power control feedback to achieve performance and target lifetime with reduced testing requirements. Parametric study considered operating time, ambient temperatures, and materials to investigate the impact of each on the temperature distribution in smartphones has been presented.

Volume 11, issue 2, 2020, pp.97-106.

2. Charging strategy effect on lithium polymer battery capacity: A case study

Dimitrios Rimpas¹, Athanasios Kiatipis²

¹ Department of Electrical and Electronic Engineering, University of West Attica, Egaleo, 12244, Greece.

² Department of Mechanical Engineering, University of West Attica, Egaleo, 12244, Greece.

Abstract: Since the invention of lithium ion batteries, charging strategies have met great acknowledgment and research over the years. In this paper, a laptop with lithium polymer battery is monitored via three widely used tools, during various operational and charging loads. Several key values are obtained in order to evaluate the correlation between battery cycles, charging percentages and depth of discharge. Ultimately the results show that massive discharges and continuous operation with the device plugged should be avoided, though high load tasks require the AC charger to be connected. Ensuring that battery stays at safe temperature and charging ranges can expand cell life and state, as well as prevent lithium deposits inside the battery.

3. Potential and readiness analysis of renewable energy in the GCC states

Mohammad A. T. Alsheyab

Senior Expert of Environmental Development at the Ministry of Development Planning and Statistics and Adjunct Professor at Qatar University, Qatar.

Abstract: The paper aims at better understanding of the opportunities and potentials of the deployment of clean energy in the region of highest fossil fuel reserves in the world, the gulf cooperation council (GCC) states, by conducting a comprehensive analysis of the seventh sustainable development goal (SDG7) in the GCC states context including a detailed description of its targets, indicators as well as interrelatedness with the other SDGs. In line with that, the paper evaluated the renewable energy potential in the GCC states, its readiness to deploy and the constrains still to overcome. Analysis showed that GCC region has got a high potential of solar and wind energy, and good readiness for its deployment. The potential of solar energy resources in GCC states varies between 5.1 to 5.9 kWh/m2 year. The average wind speed in GCC countries is between 3.5 -6 m/s, with the highest average of 6 m/s in Qatar and lowest average of 3.5 in Saudi Arabia.

4. Hydropower exploration in natural areas and environmental licensing procedures in Brazil

Marco Aurélio dos Santos1, Orleno Marques da Silva Junior2, André Andrade3

1 Energy Planning, Federal University of Rio de Janeiro. COPPE / UFRJ, Brazil.

2 Institute of Scientific and Technological Research of the State of Amapá, IEPA, Brazil.

3 Brazilian Institute of Environment and Renewable Natural Resources – IBAMA, Brazil.

Abstract: The participation of hydroelectric plants in the Brazilian electric energy matrix reached 90% in the 1990s. However, due to the environmental impacts that these projects cause and the insertion from other sources, this participation declined, with prospects of reaching 42% by 2029. In the expansion planned for the hydroelectric sector, most of the projects are located in the Amazon and in small man-made hydrographic basins. In order to make new hydroelectric projects viable, several institutions have proposed modifications and improvements in the environmental licensing processes. Many of the proposed rule changes have the potential to improve, simplify or streamline the environmental licensing process; however, these changes do not face the main restrictions on the installation of new hydropower plants, especially in the Amazon region. Among the proposals of the institutions analyzed, the ones that are most supported are the inclusion of integrated environmental assessment and strategic environmental assessment as a subsidy to the assessment of environmental impact and the licensing process. Often these studies are elaborated, but they are little used or considered for decision making. Another possibility that could be effective would be the one-stop shop that would be responsible for working directly with institutions with jurisprudence on areas such as historical heritage, quilombolas and indigenous peoples. It is understood that it is necessary to advance the current environmental legislation so that it is possible to take advantage of the great hydroelectric potential that the country has and also to maintain the environmental gains achieved in the last decades.

5. Towards an inventory of the archimedean small hydropower potential of Greece

Alkistis Stergiopoulou¹, Vassilios Stergiopoulos²

¹ Institut für Wasserwirtschaft, Hydrologie und Konstruktiven Wasserbau,  B.O.K.U. University, Muthgasse 18, 1190 Vienna, (actually Senior Process Engineer at  the VTU Engineering in Vienna, Zieglergasse 53/1/24, 1070 Vienna, Austria).

² ASPETE, School of Pedagogical and Technological Education, Department of Civil Engineering Educators, ASPETE Campus, Eirini Station, 15122 Amarousio, Athens, Greece.

Abstract: The present paper describes the evaluation of the Greek Archimedean Small Hydro Resources, considering the basic data for the 14 water regions of the country, adopting a holistic assessment methodology of the total theoretical hydro potential of Greece, which could be exploited by using Archimedean Screw Turbines (ASTs). The total evaluation of the theoretical Archimedean hydropower potential of Greece, which may be produced with ASTs, is of the order of several TWh / year, with a theoretical installed capacity of screw turbines in the range of thousands MW, with important values of special capacity and special capacity density, demonstrating the major existing unexploited hydropower potential for a future true sustainable development with small hydro plants in Greece based on environmentally friendly screw turbines.