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RISS 인기검색어
- 검색키워드
- 저자 : Luai M. Alhems (검색결과 5 건)
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Assessment of solar energy potential and its deployment for cleaner production in Pakistan
Muhammad M. Rafique,S. Rehman,Luai M. Alhems 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8
This paper presents a comprehensive overview of the potential and outlook of solar energy in Pakistan as a source of renewable and sustainable energy. A detailed energy infrastructure and major reasons behind the power crisis in Pakistan are presented followed by a detailed assessment of solar energy potential. The results obtained from the solar atlas for solar irradiation and PV electricity output show a high potential of solar power throughout the country. An average value of 4.1 kWh/kWp per day is obtained from an installed capacity of 1 KWp. Furthermore, the total estimated potential of solar power in Pakistan is around 2900 GW and its effective use will help in the growth of the country’s economy by reducing the import of fossil fuels. It is foreseen that the present research will help nations develop and utilize solar power in their respective countries efficiently and effectively.
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Vertical axis wind turbine types, efficiencies, and structural stability – A Review
Shafiqur Rehman,Muhammad M. Rafique,Md. Mahbub Alam,Luai M. Alhems 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.1
Much advancement has been made in wind power due to modern technological developments. The wind energy technology is the world’s fastest-growing energy option. More power can be generated from wind energy by the use of new design and techniques of wind energy machines. The geographical areas with suitable wind speed are more favorable and preferred for wind power deployment over other sources of energy generation. Today’s wind turbines are mainly the horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs). HAWTs are commercially available in various sizes starting from a few kilowatts to multi-megawatts and are suitable for almost all applications, including both onshore and offshore deployment. On the other hand, VAWTs finds their places in small and residential wind applications. The objective of the present work is to review the technological development, available sizes, efficiencies, structural types, and structural stability of VAWTs. Structural stability and efficiencies of the VAWTS are found to be dependent on the structural shape and size.
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Experimental evaluation of solar thermal performance of linear Fresnel reflector
Shafiqur Rehman,Aftab Ahmad,Luai M. Alhems,Muhammad M. Rafique 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.9
The solar thermal performance of a 102 kW rated thermal capacity linear Fresnel reflector system was evaluated experimentally under fixed and variable airflow rate through the oil-air heat exchanger. The solar thermal system consisted of 240 mirrors (linear Fresnel solar reflectors), each of 1485 by 625 mm size to heat the thermal oil, which was used to heat the air using the oil to air heat exchanger (AHE). The results show that the actual maximum efficiency of the solar collector lies in the range of 0.28 to 0.34, whereas the calculated one is about 0.54 for the variable airflow rates. However, for a fixed airflow rate, the actual maximum efficiency is between 0.26 and 0.30. It implies that the actual solar collector efficiency is much lower than the calculated values. One of the major factors, which is not accounted for in the theoretical efficiency calculation, is the effect of dust on the primary and secondary mirrors. The investigated site is observing considerable sand movement, which is affecting the thermal output of the solar collector. The maximum heat exchanger effectiveness, ε, obtained for variable and fixed airflow conditions is 0.9 and 0.8, respectively.
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Durability of Structural Lightweight Concrete Containing Expanded Perlite Aggregate
Mohammed Ibrahim,Aftab Ahmad,Mohammed S. Barry,Luai M. Alhems,A. C. Mohamed Suhoothi 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.6
This study focuses on the development of durable structural lightweight concrete (LWC) by incorporating expanded perlite aggregate (EPA) in the range of 0 to 20% by weight. In order to ensure its durability when exposed to chloride environment, concrete was produced with low water-to-cement ratio and ordinary Portland cement (OPC) was replaced with 50% and 7% ground granulated blast furnace slag (GGBFS) and silica fume (SF), respectively. The mechanical properties and durability of concrete were assessed by determining the unit weight, compressive strength, flexural strength, drying shrinkage, chloride permeability and migration, as well as resistance of concrete to corrosion of reinforcing steel. Very importantly, thermal insulation properties were determined using a hot guarded plate. In addition, a finite element model (FEM) was prepared to study the behavior of EPA-modified concrete under seismic loading. The results showed that the unit weight of concrete was reduced by 20% to 30% when compared with the normal weight concrete (NWC). The compressive strength of the developed LWC was sufficient to be used as structural concrete, particularly of those mixtures containing 10% and 15% perlite aggregate. The durability of LWC was comparable to NWC in terms of chloride diffusion and resistance of concrete to corrosion of reinforcing steel. The tangible outcomes also include the superior thermal insulation properties of LWC compared to NWC. The greater incorporation of EPA in the concrete resulted in better behavior under seismic loading.
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A review of wind-turbine structural stability, failure and alleviation
Shafiqur Rehman,Md. Mahbub Alam,Luai M. Alhems 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.5
Advancements in materialistic life styles and increasing awareness about adverse climatic changes and its negative effects on human life have been the driving force of finding new and clean sources of energy. Wind power has become technologically mature and commercially acceptable on global scale. However, fossil fuels have been the major sources of energy in most countries, renewable energy (particularly wind) is now booming worldwide. To cope with this wind energy technology, various related aspects have to be understood by the scientific, engineering, utility, and contracting communities. This study is an effort towards the understanding of the (i) wind turbine blade and tower structural stability issues, (ii) turbine blade and tower failures and remedial measures, (iii) weather and seismic effects on turbine blade and tower failures, (iv) gear box failures, and (v) turbine blade and tower failure analysis tools.
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