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E. Firouzfar M. Soltanieh S. H. Noie M. H. Saidi 《International Journal of Environmental Science and Technology》2012,9(4):587-594
The present study attempts to use the methanol?Csilver nanofluid filled heat pipe heat exchanger and compares the effectiveness as well as the energy saving with pure methanol. A heat pipe heat exchanger has been tested in a test rig under steady-state conditions. The lengths of both the evaporator and the condenser sections of the heat exchanger were 700?mm, and its central adiabatic section had a length of 160?mm. The heat exchanger had 36 plate finned copper thermosyphons arranged in three rows. The inlet air temperature across the evaporator section was varied in the range of 33?C43?°C while the inlet air temperature to the condenser section was nearly constant to be 13?°C. First, pure methanol was used as the working fluid with a fill ratio of 50?% of the evaporator section length, and then dilute dispersion of silver nanoparticles in methanol was employed as the working fluid. The nanofluid used in the present study is 20?nm diameter silver nanoparticles. The experiments were performed to compare the heat pipe heat exchanger effectiveness and energy saving, using nanofluid and pure methanol. The inlet air relative humidity across the evaporator section was varied between 35 and 80?%. The sensible effectiveness of the heat pipe heat exchanger obtained from experiments varied about 5?C22?% for pure methanol and 9?C32?% for methanol?Csilver nanofluid. Based on these experimental results, using methanol?Csilver nanofluid leads to energy saving around 8.8?C31.5?% for cooling and 18?C100?% for reheating the supply air stream in an air conditioning system. 相似文献
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Henrik Stendal Robert Frei Sospeter Muhongo Thorkild M. Rasmussen Saidi Mnali Faustin Petro E. Brian Temu 《Journal of African Earth Sciences》2004,38(5):437-447
Gold and base metals of the Mpanda Mineral Field (MMF) is the focus of this paper. Gold veins and gold-bearing base metal occurrences are structurally controlled by conjugate sets of NW–SE and E–W trending faults and/or shear zones that crosscut high-grade metamorphic rocks and post-kinematic intrusions. It was anticipated that Palaeoproterozic country rocks could have been potential host rocks for the gold mineralisation in this area. This argumentation was based on Pb model ages of various deposits from the MMF. Recent fieldwork and Pb isotopic results presented herein indicate that epigenetic gold and base metal vein-type mineralisation in the MMF is post-Palaeoproterozoic.Our Pb isotope study concentrates on constraining the sources of metals in gold-bearing quartz reefs and base metal occurrences. Pb isotopes of whole rocks and minerals indicate that mineralisation was emplaced during the Neoproterozoic, contemporaneous with the intrusion of alkaline granites and carbonatite complexes (e.g., Sangu–Ikola carbonatite complex) at 720 Ma. The source of Pb in the mineral occurrences is compatible with that characteristic of the Palaeoproterozoic host rocks. Aeromagnetic data suggest that the gold-bearing, NNW–SSE trending area continues to the north beyond Mpanda town. Pb isotope results and aeromagnetic data have significant implications for future exploration programs within the region, in that the search should potentially focus on the defined geophysical borders and trendlines, and on Neoproterozoic, rather than Palaeoproterozoic vein systems. 相似文献
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The first and second order generating functions and the first second and third order new J-S-U-N Hamiltonians are calculated by the Hori-Lie procedure. 相似文献
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Bachaer Ayed Ikram Jmal Samir Sahal Naziha Mokadem Salwa Saidi Emna Boughariou Salem Bouri 《Environmental Earth Sciences》2017,76(24):821
Worldwide, groundwater resources have been considered as the main sources of drinking, domestic uses, industrial and agriculture water demands, especially in arid and semiarid regions. Accordingly, the monitoring of the groundwater quality based on different tools and methods becomes a necessity. The aim of this study was to apply several approaches to assess the water quality and to define the main hydrochemical process which affect groundwater of the Maritime Djeffara shallow aquifer. In addition to the hydrochemical approach, two multivariate statistical analyses, hierarchical clusters analysis (HCA) and principal component analysis (PCA), were carried out to identify the natural and the anthropogenic processes affecting groundwater chemistry. Hydrochemical approach, based on 47 analyzed groundwater samples, shows that most of samples present a sulfate to mixed chloride, with sodi-potassic tendency facies. According to their chemically composition, the HCA revealed three different groups (C1, C2 and C3) according to their electrical conductivity (EC) values: C1 (average EC = 4500 µS/cm), C2 (average EC = 7040 µS/cm) and C3 (average EC = 9767 µS/cm). Furthermore, PCA results show two principal factors account 84.05% of the total variance: (1) F1 represents the natural component, and (2) F2 symbolizes the anthropic component. Moreover, the groundwater quality map of the Maritime Djeffara shows three categories: suitable, doubtful and unsuitable water for irrigation. These different results should be taken to protect water resources in arid and semiarid regions, especially at the alluvial coastal regions. Also, they help to make a suitable planning to manage and protect the groundwater resources. 相似文献