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Lee C.-L.,Diwan University | Jou C.-J.G.,National Kaohsiung First University of Science and Technology
Fuel Processing Technology

The furnace efficiency can be maintained or improved slightly by lowering the excess air ratio and raising the air preheat temperature in the heat furnace. The results obtained with a plant-size industrial furnace show that when the excess air oxygen concentration is reduced from 4% to 3%, the furnace efficiency is raised by 0.6%. However, raising the temperature of the pre-heated air will cause a higher furnace temperature and a faster flowing speed of the air in the furnace. Thus, the heat in the radiation zone of the furnace can be evenly transmitted to shorten the time for the fuel to reach the igniting point, and reduce the heat loss from the hot air stream. This will reduce the emission of CO2 and NOx. If the temperature of the pre-heated air is raised from 200 °C to 240 °C, about 2.3 × 106 m 3 of natural gas can be saved annually to reduce 3.1 × 10 3 t of CO2 and 14.3% of nitrogen oxide emissions. Such operational adjustments of the furnace using the recovered FG will save energy, reduce CO2 emission and alleviate the adverse impact to environment. © 2011 Elsevier B.V. All rights reserved. Source

Cheng S.-J.,Diwan University
Water Resources Management

Taiwan frequently experiences heavy rainfall events during the summer. The rainfall-runoff regeneration is an important job in specific areas where excessive rainfall causes serious flooding. The primary goal of this study is to generate and understand runoff components of the watershed outlet by using a conceptual model of three linear cascade reservoirs. The conceptual model is needless to determine direct runoff and excess rainfall in advance. Every linear cascade reservoir has an independent response function with an exponential expression. The outflows of the linear reservoirs represent streamflow components of a watershed outlet during rainfall-runoff processes, in which surface runoff is considered as quick runoff, whereas subsurface and groundwater runoffs are slow runoffs. In the simulation process, mean rainfall as model inputs were estimated using the block Kriging method. Available recordings of 68 rainfall-runoff events during 1966-2002 were used as the study sample. Fifty-four events were calibrated to determine the best hydrograph parameters and were used to compare simulation precision resulting from the model with those based on the Nash with NLP. The efficacy of the proposed model was verified using the remaining 14 observed rainfall-runoff data from an actual basin. The seven averaged parameters, which were applied for verification, show that the IUH shape of quick flow is more sharp-pointed with the peak shifted forward than that of slow flow. In rainfall-runoff processes, peak discharge of quick runoff is far larger than that of slow runoff, the time it takes for the peak discharge for a quick flow is earlier than that for a slow runoff, and the base time of a slow flow is longer than that of a quick flow. Furthermore, this study also found: (1) the base time of a slow runoff hydrograph is the same as that of a total runoff hydrograph; (2) the base time of a quick runoff hydrograph is contrariwise to the value of the soil antecedent moisture; (3) an amount of quick runoff is directly proportional to that of total runoff. These analytical results reveal that the model used in this study is suitable to evaluate hydrological conditions in this and other watersheds and can be further applied to watershed management in Taiwan. © 2010 Springer Science+Business Media B.V. Source

Hsiao K.-L.,Diwan University
International Journal of Non-Linear Mechanics

A magnetic hydrodynamic (MHD) mixed convective heat transfer problem of a second-grade viscoelastic fluid past a wedge with porous suction or injection has been studied. Governing equations include continuity equation, momentum equation and energy equation of the fluid. It has been analyzed by a combination of a series expansion method, the similarity transformation and a second-order accurate finite-difference method. Solutions of wedge flow on the wedge surface have been obtained by a generalized FalknerSkan flow derivation. Some important parameters have been discussed by this study, which include the Prandtl number (Pr), the elastic number (E), the free convection parameter (G) and the magnetic parameter (M), the porous suction and injection parameter (C) and the wedge shape factor (β). Results indicated that elastic effect (E) in the flow could increase the local heat transfer coefficient and enhance the heat transfer of a wedge. In addition, similar to the results from Newtonian fluid flow and conduction analysis of a wedge, better heat transfer is obtained with a larger G and Pr. © 2010 Elsevier Ltd. Source

Lee C.-L.,Diwan University | Jou C.-J.G.,National Kaohsiung First University of Science and Technology
Environmental Progress and Sustainable Energy

Reducing the input excess air or airflow rate to a furnace or boiler will result in decreasing transmission rate of the thermal flow from the radiation zone to the convection heating surface zone in the furnace. Results of the plant-scale test presented in this article show that if the furnace is operated at 3.6 ×- 10 7 kcal/h of combustion capacity, decreasing the residual O 2 concentration in the furnace flue gas from 4% to 2.5% will save 9.3 × 10 3 m 3 of natural gas consumption, and 2.1 × 10 4 tons of CO 2 emission annually. For the boiler tested in the study, 1.8 × 10 5 m 3 of natural gas consumption and 3.9 × 10 5 tons of CO 2 emission will be reduced annually if it is operated with 90 ton/h steam yield. Hence, controlling the input excess air (or oxygen) as an important operating alternative to enhance thermal efficiency, and alleviate environmental impact of a heater furnace and boiler has been confirmed in this research. © 2011 American Institute of Chemical Engineers. Source

This study investigates the characteristics of hydrograph components in a Taiwan watershed to determine their shapes based on observations. Hydrographs were modeled by a conceptual model of three linear cascade reservoirs. Mean rainfall was calculated using the block Kriging method. The optimal parameters for 42 events from 1966-2008 were calibrated using an optimal algorithm. Rationality of generated runoffs was well compared with a trusty model. Model efficacy was verified using seven averaged parameters with 25 other events. Hydrograph components were characterized based on 42 calibration results. The following conclusions were obtained: (1) except for multipeak storms, a correlation between base time of the surface runoff and soil antecedent moisture is a decreasing power relationship; (2) a correlation between time lag of the surface flow and soil antecedent moisture for single-peak storms is an increasing power relationship; (3) for single-peak events, times to peak of hydrograph components are an increasing power correlation corresponding to the peak time of rainfall; (4) the peak flows of hydrograph components are linearly proportional to that of total runoff, and the peak ratio for the surface runoff to total runoff is approximately 78 and 13% for subsurface runoff to total runoff; and (5) the relationships of total discharges have direct ratios between hydrograph components and observations of total runoffs, and a surface runoff is 60 and 32% for a subsurface runoff. © 2010 American Water Resources Association. Source

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