Volume 1 Issue 1

Authors: A. Aboulkas; K. El harfi; M. Nadifiyine; M. Benchanaa

Abstract: Pyrolysis of oil shale/polystyrene mixture was performed in a thermogravimetric analyzer (TGA) from room temperature to 1273K, at heating rates of 2, 10, 20, 50 and 100 K/min. The global mass loss during oil shale/polystyrene pyrolysis was modelled by a combination of mass-loss events for oil shale and for polystyrene volatiles. TGA results indicate that mixture pyrolysis can be identified as three phases. The first is attributed to the drying of absorbed water; the second was dominated by the overlapping of organic matter and plastic pyrolysis, while the third was linked to the mineral matter pyrolysis, which occurred at much higher temperatures. Discrepancies between the experimental and calculated TG/DTG profiles were considered as a measurement of the extent of interactions occurring on co-pyrolysis (10% of the difference between experimental and calculated curves in the temperature range 600-900 K). The maximum degradation temperature of each component in the mixture was higher than those the individual components. The calculated residue was found to be higher than experimental. These experimental results indicate a significant synergistic effect during pyrolysis of mixture of oil shale and polystyrene. The kinetic studies were performed using Flynn-Wall-Ozawa (FWO) method. The overall activation energies were 87 kJ/mol for organic matter of oil shale, 169 kJ/mol for polystyrene and 161 kJ/mol for the mixture. Thus, it has been found that there exists an overall synergy, when two materials were pyrolysed together.

Keywords: thermogravimetric; pyrolysis; kinetics; oil shale; polystyrene.


Authors: Menglan Duan; Yongtian Kang; Baoyan Chen

Abstract: Subsea Christmas tree is one of the most important equipments in the subsea production system. The easily damaged pipelines should have stress analysis according to the standards. In this paper, authors establish pipeline optimization design model under the conditions of water depth and temperature, and then use ABAQUS software for finite element calculation of stress. By comparing with the different kinds of design results, the best one for the Christmas tree pipeline design is chosen. Results shows that the use of optimization design method can reduce cost.

Keywords: Christmas tree, pipeline, optimization design, constrained optimization ,finite element calculationzhanfeng.


Authors: Raj Mohan Singh

Abstract: Hydraulic structures are integral part of water and power infrastructure development of a country. Most of the hydraulic structures are founded on permeable foundation. There is, however, no procedure to fix the basic barrage parameters, which are depth of sheet piles/cutoffs and the length and thickness of floor, in a cost-effective manner. Changes in hydrological and climatic factors may alter the design seepage head of the hydraulic structures. The variation in seepage head affects the downstream sheet pile depth, overall length of impervious floor, and thickness of impervious floor. The exit gradient, which is considered the most appropriate criterion to ensure safety against piping on permeable foundations, exhibits non linear variation in floor length with variation in depth of downstream sheet pile. These facts complicate the problem and increase the non linearity of the problem. However, an optimization problem may be formulated to obtain the optimum structural dimensions that minimize the cost as well as satisfy the exit gradient criteria. The optimization problem for determining an optimal section for the weirs or barrages normally consists of minimizing the construction cost, earth work, cost of sheet piling, length of impervious floor etc. The subsurface seepage flow is embedded as constraint in the optimization formulation. Uncertainty in design, and hence cost from uncertain seepage head are quantified using fuzzy numbers. Results show that an uncertainty of 15 percent in seepage will result in 22 percent of uncertainty in design represented by overall design cost. The limited evaluation show potential applicability of the proposed method.

Keywords: Nonlinear optimization formulation, Genetic Algorithm, Hydraulic Structures, Fuzzy numbers, Uncertainty Characterization


Authors: John W. White; Mark J. Henderson

Abstract: Stage I C6Li and stage II C12Li were prepared using a low temperature liquid lithium route. Small angle X-ray scattering measurements of both pristine binary compounds indicated that the surfaces are highly dissected. As a result using a mixed layered graphite precursor containing pregraphitic, chemically distinct lamellar domains, both C6Li and C12Li produced an additional suite of ternary structures after successive intercalation with Li and THF. The use of a THF– Li–graphite ternary compound to entrap LiBH4 for hydride storage is explored.

Keywords: X-ray diffraction, X-ray scattering, intercalation, lithium.


Authors: Muxina Konarova; Jorge Norberto Beltramini; Gao Qing Lu; Akshat Tanksale

Abstract: The MgH2/C composite can be synthesized through decomposition of an organo-magnesium precursor under hydrogen pressure. Samples were synthesized at 250°C for 30 min, 2h and 4 h under 2MPa hydrogen pressure, respectively. XRD patterns of the MgH2/C composite exhibit pure MgH2 phase with tetragonal structure. Morphology of the MgH2/C composite exhibits porous nanostructure and shape of resultant particles varies with the synthesis time. TPD spectra of a sample synthesized at 250°C for 4h shows remarkable decrease in onset hydrogen release temperature. MgH2/C composite prepared by using organo-magnesium precursor decomposes (Tmax=325°C) at relatively lower temperature than the MgH2/C prepared by ball-milling (Tmax=380°C).

Keywords: composite material, hydrogen storage, organo-magnesium, TPD measurement


Authors: Mohammad Ameri; Behnam Tahvildar

Abstract: Iran has a special electricity market with more than 10% annual increase in electricity demand. Gas turbine power plants are recognized as the preferable technology to meet this rapid growth since they are constructed faster than other conventional plants. However, gas turbines lose a part of their power and efficiency when the ambient temperature rises. According to V94.2 model, presented in this paper, rising ambient temperature from 15ºC to 40ºC at φ=60%, decreases output power by 15%. It means that approximately 0.6% output power is lost per each 1ºC. This degradation alone has caused electricity grid of the country to lose 2000 MW from its total capacity in summer, when electricity demand is at its peak value. To economically tackle this degradation, evaporative inlet air cooling systems are planned to be used in gas turbine power plants of Iran. The objective of this study is to find those V94.2 gas power plants in the country with the proper ambient conditions for fog system application and to estimate the additional power gained by Fog for each of them. In the first part of study, thermodynamic model of V94.2 is developed to show the impact of ambient conditions i.e. temperature and humidity, on performance of this turbine. In the second part, ambient condition of existing V94.2 gas turbine power plants are checked to find their potential for Fog operation. Model of V94.2 is then utilized for estimation of the additional power gained by Fog system at the defined design points. The results of this study have shown that most of the gas turbine power plants, except those located in north and west of the country, have excellent potential for Fog operation with Evaporative Cooling Potential (ECP) of 11.5-24ºC. The results also show that Fog systems in these plants can be used as power boosters to yield additional 12.5 to 26.5 MW at the defined design points; this is a matter that makes this technology also economically attractive.

Keywords: Fog, ambient condition, gas turbine, V94.2, thermodynamic model, power augmentation


Authors: Abdel-Karim Daud; M. Ismail; Walid Kukhun; Marwan M. Mahmoud

Abstract: Hybrid power systems are based on renewable energy sources and especially on photovoltaic and wind energy systems. Software package is used to analyze measuring data for wind speed and solar radiation of two locations in Palestine (Ramallah and Nablus). Results of analysis illustrate that energy density available in wind for Ramallah site is about 2008 kWh/m2 .year, while it is 927 kWh/m2 .year for Nablus site. The daily average of solar radiation intensity on horizontal surface is about 5.4 kWh/m2 .day. A Matlab software package is used to simulate different scenarios of operation of the hybrid system by making energy balance calculations on an hourly basis for each of the 8760 hours in a year. This enable to choose the appropriate sizes of the different components for the most optimum scenario. The optimization is based on cost of generation. Results of the simulation illustrate that the most economic scenario is the scenario that uses a hybrid system mainly dependent on wind. Cost of energy (COE) in this scenario is 1.28 NIS/kWh(͠ 0.35 $/kWh). Other scenarios dependent on wind-diesel hybrid system, PV-diesel hybrid system, wind stand-alone system, PV stand-alone system, or diesel only, give results of COE greater than this value. It was concluded that none of the hybrid system scenarios analyzed could be justified to replace purchasing of electricity from the grid where the COE is 0.70 NIS/kWh(0.19 $/kWh). Keywords— Hybrid Power System; Matlab; Wind Power; Photovoltaic; Energy Cost; CO2 Production ; Weibull Distribution; Diesel Generator

Keywords: Hybrid Power System; Matlab; Wind Power; Photovoltaic; Energy Cost; CO2 Production ; Weibull Distribution; Diesel Generator


Authors: Raneesh. K .Y.

Abstract: A study was made to develop a simple conceptual daily root zone water balance model applicable to drylands enclosed by bunded fields having deep water table conditions. The soil moisture contents predicted from the model for different months were similar to that of the observed values both under control and treatmental plots while 45cm root zone depth was considered. The soil moisture contents were always higher in treatmental plots than in control plots both in observed and predicted values. The model predicted soil moisture relatively better during dry periods compared to moist periods prevailing after the receipt of the rainfall. This might be due to the moisture redistribution process in the soil after the receipt of the infiltrated rainwater, which was not considered in the model. The model predicted low values than the observed runoff in the treatment and control plots.

Keywords: bunded fields; conceptual model; dryland agriculture; horticultural crops; root zone water balance.