• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.4
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• pp.309-315
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• 2012

Catalytic combustion is generally accepted as one of the environmentally preferred alternatives for heat and power from fossil fuels, as it has the advantage of stable combustion under very lean conditions with such low emissions as UHC, CO, and NOx. In this work, therefore, comparative numerical studies on the catalytic combustion behaviors over Pd-based catalysts have been conducted with the gaseous $CH_4$, $C_2H_6$, and $C_3H_8$. In the following, after introducing the governing equations with 1D channel and Langmuir-Hinshelwood models, numerical investigations on the catalyst performance are conducted by changing such various parameters as inlet temperature, excess air ratio, and space velocity. The numerical results show that outlet temperature and conversion of $C_3H_8$ are highest among others because of its chemical structure and reactivity.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.68-78
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• 2006

In the past few years, considerable efforts have been directed towards the further development of Urea-SCR(selective catalytic reduction) technique for diesel-driven vehicle. Although urea possesses considerable advantages over Ammonia$(NH_3)$ in terms of toxicity and handling, its necessary decomposition into Ammonia and carbon dioxide complicates the DeNOx process. Moreover, a mobile SCR system has only a short distance between engine exhaust and the catalyst entrance. Hence, this leads to not enough residence times of urea, and therefore evaporation and thermolysis cannot be completed at the catalyst entrance. This may cause high secondary emissions of Ammonia and isocyanic acid from the reducing agent and also leads to the fact that a considerable section of the catalyst may be misused for the purely thermal steps of water evaporation and thermolysis of urea. Hence the key factor to implementation of SCR technology on automobile is fast thermolysis, good mixing of Ammonia and gas, and reducing Ammonia slip. In this context, this study performs three-dimensional numerical simulation of urea injection of heavy-duty diesel engine under various injection pressure, injector locations and number of injector hole. This study employs Eulerian-Lagrangian approach to consider break-up, evaporation and heat and mass-transfer between droplet and exhaust gas with considering thermolysis and the turbulence dispersion effect of droplet. The SCR-monolith brick has been treated as porous medium. The effect of location and number of hole of urea injector on the uniformity of Ammonia concentration distribution and the amount of water at the entrance of SCR-monolith has been examined in detail under various injection pressures. The present results show useful guidelines for the optimum design of urea injector for reducing Ammonia slip and improving DeNOx performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.134-142
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• 2011

Although combustion is essential in most energy generation processes, it is one of the major causes of air pollution. Exhaust pipes with circular fin were designed to study the effect of cooling the recirculated exhaust gases (EGR) of Diesel engines on the chemical composition of the exhaust gases and the reduction in the percentages of pollutant emissions. The gases examined in this study were oxides of nitrogen (NOx), carbon dioxide ($CO_2$) and carbon monoxide (CO). In addition, $O_2$ concentration in the exhaust was measured. The designs adopted in this study were about exhaust pipes with solid and hollow fins around them direct surface force measurement in water using a nano size colloidal probe technique. The direct force measurement between colloidal surfaces has been an essential topic in both theories and applications of surface chemistry. As particle size is decreased from micron size down to true Carbon nano Colloid size (<10 nm), surface forces are increasingly important. Nano particles at close proximity or high solids loading are expected to show a different behavior than what can be estimated from continuum and mean field theories. The current tools for directly measuring interaction forces such as a surface force apparatus or atomic force microscopy (AFM) are limited to particles much larger than nano size. This paper use Water and CNC fluid at normal cooling system of EGR. Experimental result showed all good agreement at Re=$2.54{\times}10^4$ by free convection and Re=$3.36{\times}10^4$ by forced air furnace.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.60-69
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• 2013

An optimum configuration of the hybrid/dual swirl jet combustor for a micro-gas turbine was investigated experimentally. Location of pilot nozzle, angle and direction of swirler vane were varied systematically as main parameters under the conditions of constant thermal load. The results showed that the variation in locations of inner fuel nozzle and pilot burner resulted in significant change in flame shape and swirl intensity due to the changes in recirculating flow pattern and minimum flow area near burner exit, in particular, with the significant reduction of CO emission near lean-flammability limit. In addition, it was observed that the co-swirl configuration produced less CO and NOx emissions compared to the counter-swirl configuration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.54-61
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• 2018

Incomplete combustion in automotive engines is a major cause of harmful exhaust gases. In this study, to prevent incomplete combustion and reduce exhaust gas emissions, a gasket blade for increasing the air velocity was applied to the intake manifold, and the change in exhaust gas was investigated theoretically and experimentally. First, simulation analysis for flow according to the number and angle of the gasket blade was performed using a 3D flow analysis program. As an analysis result, the internal average velocity of the gasket blade was optimum at 6-blade with an angle of $30^{\circ}$. Based on the simulation results, experiments were conducted to verify the effects of the gasket blades on the exhaust gas in a non-load engine simulation system. As the engine speed was increased from 2000 to 4000 rpm, exhaust gases of HC, CO, and NOx decreased by 23.4%, 16.5%, and 3.8%, respectively, and the emission decreasing effect was reduced.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.435-442
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• 2021

Mn-added Barium hexaaluminates were manufactured by homogeneous precipitation method using Urea. The effects of water wash and dry temperature were analyzed by thermal weight analysis, X-ray diffraction analysis, and scanning electron microscopy. Catalysts that went through the filtration step only produced pure hexaaluminate images compared to those that went through the water wash step. During the drying process, it seems that the remaining urea helps dehydration of the precursor and affects the phase shift of gibbsite to boehmite, which is easy to convert to pure hexaaluminate. The catalyst WO200 gave the best performance in the methane combustion reaction, and NOx was not emitted in the reaction for all catalysts. Hexaaluminates were found to affect reducing the highest CO emissions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.371-376
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• 2012

The experimental test was conducted for a heavy-duty DME bus in JE-05 exhaust gas test mode using a chassis dynamometer, exhaust gas analyzers, and a PM measurement system. The heavy-duty DME bus was not equipped with after-treatment systems such as DOC or DPF. The dynamic behavior, emission characteristics, and fuel economy of the bus were investigated with an 8.0-liter, 6-cylinder conventional diesel engine. The results showed that the dynamic behavior in DME mode was almost the same as in diesel mode. However, there was little difference among the two operation modes for $NO_x$ and CO emissions. THC emissions were lower for DME mode than for diesel mode. Also, the amount of PM emissions was remarkably lower than for the diesel mode because DME contains a greater amount of oxygen than diesel. The data showed that $CO_2$ emissions were almost similar in the two modes but fuel economy (calculated using heating value) was lower for DME mode than for diesel mode.

• Journal of the Korean Institute of Gas
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• v.18 no.6
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• pp.7-13
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• 2014

As the interest on the air pollution is gradually rising up at home and abroad, automotive and fuel researchers have been working on the exhaust emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative after-treatment systems, using clean (eco-friendly alternative) fuels and fuel quality improvement. This research has brought forward various main issues : whether PM emissions should be regulated for diesel and gasoline vehicles and whether gasoline and LPG powered vehicles can be further neglected from PM emission inventories. Finally, the greenhouse gas ($CO_2$, $CH_4$, $N_2O$) regulation has been discussed including automotive emission regulation. The greenhouse gas and emissions (PM) particle of automotive had many problem that cause of ambient pollution, health effects. This paper discussed the influence of LPG fuel on automotive cold startability and exhaust emissions gas. Also, this paper assessed emission characteristics due to the test temperature. These test temperature were performed by dividing the temperature of the test mode and the lowest local temperature in winter. Through this study, the correlation of cold startability, exhaust emission and greenhouse gas emission was analyzed.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.762-767
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• 2016

High thermal efficiency and the ability to use various types of fuel are a few of the many advantages of diesel engines. However, a major disadvantage is that their exhaust emissions are more harmful to humans and the environment than that of conventional engine. Consequently, the provisions of the international emissions standards for diesel engine equipped passenger cars, commercial vehicles, and ships have become more stringent. These standards include the EU Euro 6, the IMO MEPC Tier 3, and the US EPA Tier 4. Ryu et al. published a study that applied fuel additives to two-stroke diesel engines. In this study, a four-stroke diesel engine using diesel oil for a generator is utilized as the test subject, and an experiment is performed to verify whether fuel additive can be used to improve performance and exhaust emissions. In addition, this experimental study presents research results for the application of fuel additives in both two-stroke and four-stroke diesel engines. The experimental results were compared and analyzed by placing an oil-soluble calcium-based organometallic compound in diesel oil. The results confirmed that the addition of fuel additive improved the performance (fuel consumption rate, exhaust gas temperature) and exhaust emissions (NOx, CO) of the diesel engine.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.421-428
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• 2007

This paper investigates the combustion and emission characteristics of a compression ignition engine fueled with neat and blended Shell's gas-to-liquid (GTL) fuel, which was derived from natural gas through the Fischer-Tropsch process. The experiments were conducted in a 6-cylinder DI diesel engine with pump timing settings of $6^{\circ},\;9^{\circ}\;and\;12^{\circ}$crank angle before TDC over ECE R49 and US 13-mode cycles separately and compared to a conventional diesel fuel. The results show that GTL exhibited almost the same power and torque output, improved fuel economy and effective thermal efficiency. It was found that GTL displayed lower peak in-cylinder combustion pressure and maximum heat release rate (HRR), the timings of the peak pressure and the maximum HRR were generally delayed, and the combustion durations were almost equivalent for diesel and GTL under the same speed-load condition. The results also indicate that, compared to diesel fuel, GTL blends showed a trend forward decreasing four regulated emissions simultaneously and a higher GTL fraction in blends contributing to further reductions in the emissions. In particular and on average, neat GTL significantly reduced HC, CO, NOx and PM by 16.4%, 17.8%, 18.3% and 32.4%, respectively, for all cases.