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Year 2010

Volume 1, Issue 2 April - June 2010

Abstract: This paper highlights the current status of the largest coal preparation plant in Vietnam and suggests Cleaner Production (CP) options to address some problems of the plant. In the year 2005, about 30% of run-of-mine (ROM) coal was washed in coal preparation plants, the remaining treated in coal mining companies. The plant considered in this study had a production capacity of 6.1 million tons of ROM coal in 2005. Results of the preliminary assessment showed that the plant was facing several problems such as high amount of fine coal in ROM coal, high amount of magnetite loss, low efficiency operation of the cyclone classifier system, high ash content in the fine coal product, and high amount of coal slurry. CP options along with a simple economic analysis have been suggested to address all these issues.

Key words: Cleaner Production; Coal preparation; Vietnam.
(147 K)
Abstract: Dissolved oxygen, biochemical oxygen demand, nitrate-nitrogen, total phosphorus, fecal coliform bacteria, and suspended solids were used to evaluate water quality in the northeastern rivers of Thailand: Lam Chi, Lam Pao, Lam Seaw, Loei, and Nam Oon. The mean observed values of the six water quality parameters in each river over a 5-year period (2003–2007) were used to compute the present water quality index (WQIpresent) of each river in the wet (June–November) and dry (December–May) seasons. The mean observed values of the study parameters of each river by season over a 14-year period (1994–2007) were used to build a set of time series models for predicting the values of the associated parameters of each river in the next 5-year period (2008–2012). These mean predicted values were used to compute the WQIfuture by season for each river. According to the results, the water quality at many sampling stations was in good condition. However, the water quality in Lam Chi and the Loei River will tend to decrease in the next 5-year period unless proper management is undertaken to reduce the concentrations of certain contaminants such as total phosphorus and fecal coliform bacteria in the rivers. This study revealed that the time series models with the best predictions among the stations were often not the same types. Several time series models should be used and their prediction accuracy should be compared. Water quality parameters considered in developing a WQI and the index use may be limited to a watershed for which it has been developed.

Keywords: freshwater; aquatic system, physical; chemical; geometric mean.
(669 K)
Abstract: This paper applies the D2-law to a group of heterogeneous size of biodiesel drops in order to determine the time evolution of the drop-size distribution and its burn-out time. Experiments to determine initial drop distribution data, used for predicting the evaporation time, have been performed on a biodiesel spray issuing from a small scale industrial burner. The measured drop-size distribution has been first transformed into a dimensionless form, called mass-based drop-diameter distribution, before its time dependent distribution and the evaporation time are calculated. It is found that the D2-law, originally applied for determining the evaporation time of a droplet, can be adapted well to calculate the time evolution of the drop-size distribution and its evaporation time. The dimensionless evaporation time is shortest for a group of mono-sized drops and prolonged for a drop-size distribution provided that they are at the same initial mean diameter. Furthermore, if the initial dimensionless mass distributions contain high proportion of small drops; it is prone to evaporate faster than those containing larger drops. The dimensionless evaporation times obtained from this study are the analysis results of the drop-size distribution along the line-of-sight measurement data. In this work, the variations of the volume concentration along the line-of-sight are omitted.

Keywords: Biodiesel spray, Burn-out time, D2-law, Dimensionless mass-based drop-diameter distribution, Time evolution mass-based drop-diameter distribution.
(403 K)
Abstract: The two major biomass resources being used for power production in Thailand are bagasse, a byproduct of sugar production, and rice husk, which remains after milling rice. Larger resources are still reportedly unused in the two agricultural sectors sugar and rice, which are the field-based commodities sugar cane trash and leaves and rice straw. An in-depth analysis was performed on the energetic use of bagasse in the sugar industry. Considering the present utilization pattern and efficiencies both in the power production and in the sugar milling process, it was found that there is still a large potential available for excess power production from bagasse in sugar mills. Rice husk has widely been used leading to local shortages in supply and increasing costs of the resource. The field residues are mainly unused for power production probably because of uncertainty in logistics and prices. For all present and possible biomass power routes LCA (Life-cycle Analysis) was conducted to establish the respective figures on energy balance and greenhouse gas (GHG) emissions. These figures were compared to the conventional power sector in Thailand to establish the net savings effect of the utilization patterns. The best results were compiled for bagasse since other resources need more fossil energy input into preparation and transport. Finally, the production costs per unit of electricity were calculated to demonstrate the viability, under the present condition in Thailand, for the power export to the national grid. The options in the rice sector lead to unfavorable economic results whereas in the sugar sector good returns are possible.

Keywords: Biomass Resources, Power Production, Energy Balance, Greenhouse Gas Balance, Sustainability.
(96 K)
Abstract: This paper proposes the application of ant colony optimization (ACO) to solve a static transmission expansion planning
(STEP) problem based on a DC power flow model. The major objective is to minimize the investment cost of transmission lines
added to an existing network in order to supply the forecasted load as economically as possible and subject to many system
constraints i.e. the power balance, the generation requirements, line connections and thermal limits. The Garver's six-buses system, is
analyzed to appraise the feasibility of the ACO. The experimental results obtained by ACO are compared to those obtained by the
conventional approaches of the Genetic Algorithm (GA), and the Tabu Search (TS) algorithm. The results show that the ACO
method outperforms other methods in convergence characteristic and computational efficiency.

Keywords: Ant colony optimization, Genetic algorithm, Power system planning, Tabu Search algorithm, and Transmission Expansion Planning.
(198 K)
Abstract: The Asian Dust Aerosol Model 2 (ADAM2) was developed to enhance the ability to deliver timely and quality sand and dust storm forecasts to all Asian countries that might be affected by such storms. The ADAM2 model, modified from the operational ADAM/ADAM1 model used by the Korea Meteorological Administration, utilizes statistically-derived threshold wind speeds with the use of 3 hourly reporting WMO surface data in the whole Asian domain (60-160E, 10-60N) for the period of 1998 to 2006. This also uses the parameterized emission reduction factors due to the vegetation in the Asian dust source region with the use of a Normalized Difference Vegetation Index (NDVI) obtained from Spot/Vegetation product of Maximum Value Composite Syntheses for the same period. Both the threshold wind speeds and the emission reduction factors due to the vegetation vary with time and surface soil types (Gobi, Sand, Loess, and mixed soil). A performance test of the ADAM2 model was conducted with observed PM10 concentrations at some monitoring sites in the source region and the downstream region of Korea for the whole months of May and December in 2007. It was found that the ADAM2 model was able to simulate quite well most of Asian dust-storm occurrences in the source region and dust events observed in Korea. The model simulates quite well the starting and ending times of the dust storms in the source region within 10 % margin of error with the observed surface PM10 concentration. In the downstream region of Korea, the starting and ending times of dust events were well-simulated; however, the surface PM10 concentration was slightly overestimated for some dust events. Nevertheless, there is great potential for the ADAM2 model to be used as an operational Asian dust forecast model for Asia.

Keywords: ADAM, Asian dust source region, Emission reduction factor, NDVI, Threshold wind speed.
(891 K)
Abstract: This study investigates the effects of ethanol-blended gasoline with oxygenated additives on a multi – cylinder Spark Ignition (SI) Engine. The experiments were conducted in two stages. In stage I, the test fuels were prepared using 99.9% pure ethanol and gasoline with a cycloheptanol blend, in the ratio of E69.5 + 0.5 cycloheptanol, E64.6 + 0.4 cycloheptanol, E59.7 + 0.3 cycloheptanol, E49.8 + 0.2 cycloheptanol. The remainder was gasoline. In stage II, the test fuels were prepared using 99.9% pure ethanol and gasoline with cyclooctanol blend, in the ratio of E69.5 + 0.5 cyclooctanol, E64.6 + 0.4 cyclooctanol l, E59.7 + 0.3 cyclooctanol, E49.8 + 0.2 cyclooctanol. The remainder was gasoline. Performance and emission tests were conducted on a multi – cylinder SI Engine coupled with an eddy current dynamometer. The emission tests were measured using an exhaust gas analyzer. The experimental results proved that the blend increased brake thermal efficiency more than a sole fuel, such as gasoline. The emission tests found that the CO slightly decreased, while HC and O2 increased moderately and CO2 and NOx appreciably decreased. In addition, combustion analyses were made with the help of combustion analyzer, in which cylinder pressure and heat release rate were analysed.

Keywords: CO – Carbon monoxide, HC – Unburnt Hydrocarbon, CO2 – Carbon dioxide, O2 – Oxygen, NOx – Oxides of Nitrogen, Ethanol, Cyclooctanol, Cycloheptanol.
(501 K)
 

 

ISSN: 1906-4918
Frequency: Quartery
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