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Aims and Scope
Editorial Board

1. Graphene nanosheets coating method as a new passive cooling alternative for printed-circuits board and microprocessor of laptops - CFD analysis study

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. Thermal management of handheld systems such as laptops is becoming increasingly challenging due to increasing power dissipation. The power dissipated per unit area on the laptop electronic chips is increasing while the area of the chips itself it decreasing, resulting a high heat flux that causes an increase in temperature. The increasing temperature adversely affects the performance of laptops and in many cases leads to failure through such modes as thermal fatigue and dielectric breakdown. In this work, three dimensional steady state CFD model of a laptop motherboard is presented. The model accounts for heat transfer for both natural convection and radiation to the ambient air temperature. 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. An alternative design for the cooling of laptop microprocessor using only passive cooling is proposed. The results showed that the assembled a thin plate of a copper material coated with graphene and use it as a heat sinks with the microprocessor of the laptop providing an efficient and economical solution in thermal management. Considerable drop in microprocessor temperature is obtained through the heat dissipation path suggested in the new design. The proposed passive cooling solution has the advantages of fanless operation compared to the existing active cooling solutions such as the noise-free operation, lower energy consumption and higher reliability. We hope this work may open the way for huge boost in the technology of electric cooling by innovative manufacturing techniques.

Volume 11, issue 3, 2020, pp.145-156.

2. A first CFD study of small hydro energy recovery from the attica water supply network

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 proves that the vast water supply infrastructure of Athens and the region of Attica could produce useful hydropower. The first aim of this paper is to present the unconventional small hydro philosophy of recovering the hydraulic energy wasted in the existing break pressure devices and energy dissipating structures of the Water Supply Network of Athens, the capital of Greece and of the whole Attica region.  The paper discusses themes concerning the replacement, in this large drinking water infrastructure, of all the existing break pressure devices, by a series of small hydro plants and also the efficient ways by which such small unconventional hydro schemes could be realized.  The second aim of the paper is to highlight some important CFD simulation features which however needs further investigations and to present preliminary some Flow-3D results concerning the hydrodynamic performances of this series of small hydro plants harnessing the important wasted hydraulic energy of the Attica Water Supply Network.

3. Development of biogas resources and technologies in Ghana, a survey

Edward A. Awafo¹, Victor K. Agyeman²

¹ Department of Mechanical and Manufacturing Engineering, University of Energy and Natural Resources, Sunyani, Ghana.

² Council for Scientific and Industrial Research, Box M32, Airport, Accra, Ghana.

Abstract: Due to rapid global population growth and urbanization, there is corresponding increasing demand for energy. This increasing demand has necessitated the need to explore alternative sources of energy. Besides the growing energy demand, issues of environmental protection and climate change have risen to the top of global politics, leading to increased interests in renewable energy sources. One of these renewable energy sources with very diverse applications is biogas. Biogas, like natural gas, can serve as cooking fuel, transportation fuel, and as source for electricity generation, making it a very versatile fuel. Biogas is produced from several organic feedstocks, using anaerobic digestion technology. The technology has not developed as expected in Ghana despite reported enormous feedstock potential mainly due to, lack of data on specific areas where feedstocks can be assessed and the corresponding specific biogas potential, among other reasons. This paper surveys specific areas across Ghana where the diverse biogas raw materials are concentrated. The paper also studies existing biogas technologies and their potential utilization in various economic sectors of Ghana where their application will have the highest socio-economic impact. Technical expertise and technology transfer options for the biogas technologies needed in Ghana were also assessed. The survey showed that the most common feedstock types, readily available in Ghana for anaerobic digestion are agricultural residues and food-processing residues, livestock manures, slaughterhouse wastes, municipal solid waste (organic fraction) and municipal sewage sludge. Agro-industries that process cassava waste, rice residues, palm oil residue, fruit processing waste and shea cake are the key agro-industries with very high biomass feedstock potential in Ghana. Each of the different feedstock surveyed showed methane potential in excess of 10,000,000 m³CH₄ in each of the regions. The survey also showed that biogas plants in use in Ghana are either the small to medium scale (10 m³ to 100 m³) fixed-dome digester or the floating drum digesters and two functional industrial scale Upflow Anaerobic Sludge Blanket (UASB) plants and the Ccontinuous Stirred Tank Reactor (CSTR). Some economic sectors that will be impacted from the dissemination of biogas technology are agriculture, waste management, energy and climate change, health and social benefits such as job creation and improved well-being. The paper concludes that there are skills and expertise in Ghana to manage small to medium scale biogas digesters, but on the industrial scale, there exists limited expertise in the design, installation, operation and maintenance of the plants.

4. Geothermal Direct Use for Snapper Fishpond Heating at Yogyakarta

Allen Haryanto Lukmana, Ria Ayu Rifani, Rahma Kumalaningtyas

Universitas Pembangunan Nasional Veteran Yogyakarta, Faculty of Mineral Technology, Petroleum Engineering, Indonesia.

Abstract: Surface manifestations of the geothermal activity with hot brine water temperatures approximately 44°C are found in Parangwedang, Parangtritis, Yogyakarta, Indonesia has the potential for direct utilization of geothermal energy. This study discusses a design of geothermal direct utilization for Snapper fishpond heating system by using brine to cultivate Snapper fish, which aims to maintain the ideal temperature for its growth, so it can grow faster than usual. The fishpond was designed to can be used for 3000 Snapper fishes. Water heating uses brine from the nearest hot springs with a temperature of 44°C and a mass flow rate of 1 kg/s within 100 meters with a height of 10 meters from the utilization site. It is using a double pipe heat exchanger system so that the water in the environment with a temperature of 24℃ becomes the appropriate temperature for Snapper fish cultivation, which is 28°C with the energy needed to raise the temperature is 68.1 kW. Economic analysis shows an IRR of 41% and a positive NPV with a pay-out time of 3 years. So, the Snapper fishponds heating system as geothermal direct utilization deserves to be developed.

5. Surface modification of Ti 6Al4Valloy coated (HAp-collagen) by spin coating method

Dunya Abdulsahib Hamdi¹, Abdul Rahman Najeem Abed²

¹ Department of Prosthetics & Othotics Engineering Department, Al Nahrain University, Baghdad, Iraq.

² Department of Mechanical Engineering Department, Al Nahrain University, Baghdad, Iraq.

Abstract: Bone and blood are the most implanted tissue. The collagen and substituted hydroxyapatite are major solid components of human bone. In the present study, a modest attempt has been tried to use a different method. The techniques involve the coating materials (collagen and hydroxyapatite) and the base materials Ti alloy. The aim of the paper to use spin method to coating Ti6Al4V alloy with HAp (1, 2, 3) g + (0.5 collagen) The X-ray diffraction test results show nano-size crystal structure on the coated film. By Increasing in concentration of HAp leads to an increase in thickness of film, (25-40) μm and that is clear in the results of scanning electron microscopy SEM and optical microscopy. From SEM results, the aggregation HAp nanoparticles are confined to their nano size .Also collagen with graded porosity, the mean diameter of pore in nm this type of scaffold can be used to tissues that belong to the success of the solution preparation method and use spin coating method.