Authors:Duy-Cuong Nguyen, Seigo Ito First page: 1 Abstract: AgInTe2 micron-particles were synthesized by mechanical ball milling method. Only AgInTe2 phase was obtained in the powder after ball milling from the mixture of elements (Ag, In, and Te). AgInTe2 particles had the variation in the size and the biggest particle was approximately 2 µm. AgInTe2 solar cells were fabricated as <AgInTe2/In2S3/TiO2/FTO> superstrate structure by doctor-blade printing, and were annealed at various temperatures under nitrogen ambient. AgInTe2 after annealing showed high crystallinity and two band gaps of 0.67 and 0.86 eV. Although no photocurrent was observed after annealing below 350 °C, the photocurrent was observed in AgInTe2 superstrate solar cells after annealing over 400 °C. The short-circuit photocurrent density strongly increased up to 18 mA/cm2 for the samples annealed at 600 °C for 5 min.Key words: AgInTe2; Solar cells; Printing method PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.536 Issue No:Vol. 4 (2012)
Authors:Ashwith K. Chilvery, Ashok K. Batra, Padmaja Guggilla, R. B. Lal, Raja Surabhi First page: 6 Abstract: Organic solar cells hold the potential of low-cost production as compared to inorganic solar cells, as well as the increase in efficiency. To realize these possibilities, the key is to fabricate most of the functional films in requisite structures via ambient solution-processed techniques. The PEDOT: PSS films, which are commonly used as an anode layer in organic electronic devices, were deposited on large-area ITO glass substrates under optimized conditions. The spin, spray, brush and brush+spray-coating techniques were utilized to examine their suitability in the fabrication of organic solar cells (OSCs). The films were characterized for their morphology, molecular structure, optical and electrical properties and results are compared with the existing data. A smooth and thin films of PEDOT: PSS were obtained by “Spray+Brush” coating method with attractive sheet-conductivity having potential in fabricating OSCs with different architectures.Key words: Organic solar cells; PEDOT: PSS films; Solution-processed techniques PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.528 Issue No:Vol. 4 (2012)
Authors:E. Z. Ibrahim First page: 12 Abstract: Heat transfer, friction factor and enhancement efficiency characteristics in an elliptic tube fitted with elliptic rings have been investigated experimentally. In the experiments, air was used as the tested fluid with a Reynolds number range of 10000 to 32464. The experimental results show a considerable increase in friction factor and heat transfer over the plain tube under the same operation conditions. Over the range investigated, the Nusselt numbers for both employed enhancement devices with different pitches are found to be higher than that of the plain tube. It was found that the best overall enhancement was achieved with pitch = 3d. The results obtained are correlated in the form of Nusselt number and friction factor as a function of Reynolds number and pitches. The results were compared with circular tubes have the same test conditions to show the difference between the circular and elliptic tubes.Key words: Heat transfer enhancement; Elliptic tube PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.549 Issue No:Vol. 4 (2012)
Authors:SUN Yudong, YANG Chaohe, LIU Ziyuan First page: 20 Abstract: 14 spent catalysts, which were sampled from a commercial residue hydrotreating unit at the end of an operation cycle, were analyzed by SEM to describe elements distributions along the radial direction of particles. Different from laboratory equipment, on the whole, V, Ni and S showed U-shaped pattern along the radial direction of spent catalysts. The catalyst bed has been penetrated by deposited metals and deposited massive metals on catalyst, so the pore size of catalyst decreased, diffusion resistance increased and reactants entered internal of the catalysts more difficultly. Most of the organometallic compounds hydrotreated and deposited on outside of the catalyst particles. It is showed that metals deposited on catalyst in forms of metal sulfides because the points of high metal content also have high sulfur contents unexceptionally. The structure of high metal deposition catalyst was destroyed obviously or massive irregular material has deposited on the external surface. It is verified by SEM that there is no any distribution law for deposited elements along the bed height. The change laws of deposited elements along the bed height and radial direction of particles were influenced by various factors in commercial residue hydrotrating.Key words: Residue hydrotreating unit; Spent catalyst; SEM PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.512 Issue No:Vol. 4 (2012)
Authors:Chakkraphan Thawonngamyingsakul, Tanongkiat Kiatsiriroat First page: 25 Abstract: This paper presents a potential of a solar organic Rankine cycle (ORC) with evacuated-tube solar collectors with FR(τα) of 0.81, FRUL of 2.551 W/m2K as heat source for generating electricity under the climate of Thailand. The power output of the ORC power plant was 280 kW and the ORC working fluid was R245fa. The weather conditions of Chiang Mai (18.783 oN, 98.983 oE ), Ubon Ratchathani (15.233 oN, 104.783 oE), Hat Yai (6.91 oN, 100.43 oE) and Bangkok (13.66 oN, 100.56 oE) represented the northern, northeastern, southern and central part of Thailand, respectively were taken as the input data of the calculations. It could be found that at Chiang Mai, the levelized electricity cost was lowest which was 0.37 USD/kWh and the annual solar-to-electricity efficiency was 4.44%. At Bangkok and Ubon Ratchathani, the levelized electricity costs were slightly higher than that of Chiang Mai. At Hat Yai, the levelized electricity cost was found to be highest which was 0.43 USD/kWh. Key words: Solar organic rankine cycle; Solar collector; Electrical power generation; Performance analysis; Levelized electricity cost PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.558 Issue No:Vol. 4 (2012)
Authors:Arash Shadravan, Mahmood Amani First page: 36 Abstract: On April 20, 2010, BP’s Deepwater Horizon oil rig exploded in the Gulf of Mexico. This turned out to be one of the worst environmental disasters in recent history. This high-profile blowout at the Macondo well in the Gulf of Mexico, brought the challenges and the risks of drilling into high-pressure, high-temperature (HPHT) fields increasingly into focus. New Technology, HSE regulations, new standards, such as newly recommended procedures by the American Petroleum Institute (API), and extensive training programs for the drilling crew seem to be vital in developing HPHT resources. High-pressure high-temperature fields exist in Gulf of Mexico, North Sea, Southeast Asia, Africa and the Middle East. Almost a quarter of HPHT operations worldwide are expected to happen in the American continent particularly in North America. Major oil companies have tried to identify key challenges in HPHT development and production, and several service companies have offered many insights regarding current or planned technologies to meet these challenges. However, there are so many factors that need to be addressed and learned in order to safely overcome the challenges of drilling into and producing from HPHT oil and gas wells.Drilling into HPHT wells is a new frontier for the oil and gas industry. The growing demand for oil and gas throughout the world is driving the exploration and production industry to look for new resources. Some of these resources are located in deeper formations. According to US Minerals Management Service (MMS), over 50% of proven oil and gas reserves in the US lie below 14,000 ft. subsea. As we drill into deeper formations we will experience higher pressures and temperatures.Drilling operations in such high pressure and high temperature environments can be very challenging. Therefore, companies are compelled to meet or exceed a vast array of technical limitations as well as environmental, health and safety standards. This paper explains the technological challenges in developing HPHT fields, deepwater drilling, completions and production considering the reports from the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), formerly known as the Minerals Management Service (MMS). It reviews the HPHT related priorities of National Energy Technology Laboratory (NETL), operated by the US Department of Energy (DOE), and DeepStar Committees for Technology Development for Deepwater Research. PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.635 Issue No:Vol. 4 (2012)
Authors:Jerome Rajnauth, Maria Barrufet First page: 61 Abstract: Natural gas and energy resource management is a major challenge in the rapidly changing global and business environment. Increase in gas recoveries and gas production have led a major review in the ways of transporting natural gas energy. Monetizing gas has now become a high priority issue for many countries. Natural gas is a much cleaner fuel than oil and coal especially for electricity generation.Interest in gas hydrate being used as a means of transporting natural gas has increased over the last decade. New technology development has been focusing on using gas hydrates as a way of converting gas to solids to transport to markets around the world. Gas hydrate may be a viable means of storing and transporting gas but more focus should be given to some critical considerations for this gas hydrate development.This paper would discuss some of these issues as we move towards monetizing gas in the form of hydrate. These include energy balance in hydrate formation and re-gasification, storage of the hydrate, form of transporting the hydrate and distances to be transported. Other important factors are re-gasification technologies, economics compared to other gas transportation modes, environmental, climate and other issues. PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.569 Issue No:Vol. 4 (2012)
Authors:H. M. Ramos, M. Simão, A. Borga First page: 69 Abstract: This paper deals with new design of low head turbines, as feasible solutions to solve the lack of energy in rural and remote areas, or to provide energy from urban water pipe systems. Propeller turbines are then the subject of this research because they are suitable for small heads, discharges with little variability, easy to manufacture and with low costs associated. Hence, the aims are the design of quite simple tubular propeller turbines and the analysis of hydrodynamic behaviour for different number and configuration of blades, based on CFD analyses and experimental tests development. An advanced hydrodynamic code based on the finite volume method, as well as blades configuration and mesh specific models are used for the impeller and the turbine design. The blade geometry is optimized using mathematical formulations and experimental results, concerning the possible range of operation under best efficiency conditions. Performance curves are obtained for typical characteristic parameters allowing comparisons between CFD and experimental results. Based on the similarity theory applied to turbomachines it is possible to evaluate the hydrodynamic behaviour through a tubular propeller for different sizes, in a scale model application. PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.142 Issue No:Vol. 4 (2012)
Authors:Debabrata Das, R. Srinivasan First page: 85 Abstract: More than two-thirds of the population lives in rural India. Even after six decades of independence and two decades of economic liberalization, it remains the bitter truth. This study assumes greater significance, because, majority of the rural people are still dependent on biomass fuel for cooking. A reduction in this could help India in greatly reducing the indoor as well as environmental pollution levels; thus helping in containing global warming. It would also help in controlling the health hazards caused due to the indoor pollution in the rural economy; which in effect would help the government in reducing the spending on public health. To make this happen, the government should make the distribution system of kerosene and Liquefied Petroleum Gas (LPG), efficient. This study could be useful not only to India, but to many other economies that are on the threshold of transition; where majority of the population, still lives in the rural areas, and are predominantly dependent on agriculture for their livelihood. This study was undertaken with the objective of analyzing the socio-economic conditions of rural poor in India with respect to their primary energy consumption viz. cooking fuel and impact on health. The study conducts a questionnaire based survey on demographic, economic, and perceptible parameters on modern fuel such as kerosene and LPG; using logit model to identifying variables useful for the study. PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.226 Issue No:Vol. 4 (2012)
Authors:G. O. Avwiri, C. P. Ononugbo First page: 92 Abstract: The activity concentrations and the gamma-absorbed dose rates of the terrestrial naturally occurring radio nuclides viz. 226Ra, 232Th and 40K were determined in soil samples collected from twelve oil fields and their host communities, using gamma ray spectrometry. The soil activity ranges from 10.10 to 41.23 Bq/kg for 226Ra, 7.42 to 30.31 Bq/kg for 232Th and 92.42 to 482.79 Bq/kg for 40K with mean values of 19.16, 21.26 and 224.29 Bq/kg, respectively for host community soil. In the field soil sample, the activity concentration ranges from 16.27 to 52.19 Bq/kg for 226Ra, 9.72 to 34.13 Bq/kg for 232Th and 134.50 to 395.15 Bq/kg for 40K with mean values of 29.61, 17.41 and 262.63 Bq/kg, respectively. The concentrations of these radionuclides are compared with the values of the control samples and the UNSCEAR, 2000 standards of 35.0, 30.0 and 400 Bq/kg for 226Ra, 232Th and 40K respectively. The measured activity concentration of 226Ra, 232Th and 40K in soil is lower than the world average except in two oil fields that 226Ra and 40K exceeded the world average. Radium equivalent activities are calculated from the results to assess the radiation hazards arising due to the use of these soil samples in the construction of dwellings. All the soil samples have radium equivalent activities lower than the limit set in the UNSCEAR report (370 Bq/kg). The overall mean outdoor Absorbed Dose rate are 32.17 and 35.45nGy•h−1 respectively for host community soil and field soil samples. The corresponding effective dose calculated has mean values less than 1.0 mSvy-1, the limit set by WHO (2008). The hazard indices calculated were all less than unity (1) showing that all the soil/sediment samples sampled are still safe for building purpose since their radiological impact is minimal. The percentage contribution of each of these radionuclide are; 64.77% for radium-226, 3.13% for thorium-232 and 32.10% for potassium-40. The entire radiation hazard indices are within the acceptable limit therefore, no immediate health risk as a result of these radionuclide but continuous exposure may result to a significant health impact. PubDate: 2012-11-30 DOI: 10.3968/j.est.1923847920120402.427 Issue No:Vol. 4 (2012)
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