• Journal of ILASS-Korea
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• v.24 no.1
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• pp.21-26
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• 2019

In Korea, Medium-duty trucks are classified into GVW (Gross Vehicle Weight) 3.5~10tons. MDTs are mostly used for logistics or delivery between regions. There have been studied on diesel fuel vehicles for SUVs(Sports Utility Vehicle) or light-duty trucks. But MDTs have been not studied. Therefore, this study have been used MDTs for characteristic exhaust emission. Test was carried out using the certification test mode (NEDC, New European Driving cycle) and the NIER mode in chassis dynamometer of the MDTs. And emission gas was analyzed for PN (Particulate Number), PN size distribution and aldehydes, VOCs (Volatile Organic Compounds), PAHs (Polycyclic Aromatic Hydrocarbons). This paper concluded that EURO-IV trucks produced more MSATs than EURO V trucks. Depending on the engine temperature, more MSATs were generated in cold temperature than in the hot start operation. However, the driving speed, the opposite results was obtained.

• Journal of ILASS-Korea
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• v.24 no.1
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• pp.8-14
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• 2019

The purpose of this study is to develop a packing-free wet scrubber to prolong the maintenance interval compared with the conventional packed bed wet scrubbers with which frequent operation stops are unavoidable to clean the packing materials. The main- and interaction-effects were quantitatively analyzed by regression analysis for the measured ammonia scrubbing data from the experiments prepared by experimental design. The scrubbing efficiency of the newly developed wet scrubber was found to be over 95% under the condition of flue gas flow rate of 90CMM and liquid-to-gas ratio $2l/m^3$ for all considered trials of experimental design. The interaction effect between the inlet duct spray and the filter was found to be important, which controls the droplet growth due to the droplet collisions between the duct- and scrubbing tower-spray. The presented methodology to analyze the impacts of operational and design factors on the scrubber efficiency showed potential for applications to optimize the future flue gas abatement process in semiconductor plants.

• Journal of ILASS-Korea
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• v.26 no.3
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• pp.149-156
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• 2021

In this study, the behavior of the droplet colliding with parallel wires was analyzed by time-delay photography. The impact behavior modes and the critical capture speed were analyzed by changing fluids, the droplet velocity, the wire diameter and the distance between wires. Seven typical modes of impacting droplet on parallel wires were observed. The tendency of mode change was generally similar when the wire diameter was changed, but the increase of the wire diameter caused the increase of the droplet velocity at which the mode changed. The modes at the highest droplet velocity were the splitting mode when the wires were closest, the passing and splitting mode in the middle, and the passing mode when the wires were farthest apart. The critical capture speed increased as the wire diameter increased and the distance between wires decreased. The ethanol droplet showed the lowest critical capture speed.

• Journal of ILASS-Korea
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• v.26 no.3
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• pp.111-119
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• 2021

Deteriorated agricultural diesel engines using mechanical fuel injection systems have low fuel injection pressures. And they are not equipped with an exhaust gas abatement device, so it produces a lot of exhaust gas. Remanufactured used injectors can reduce emissions because spray characteristics are improved. In addition, remanufacturing is environmentally friendly and economical compared to producing new parts. For efficient injector remanufacturing, it is necessary to conduct a comparison experiment on the spray characteristics of an used mechanical injector and a new injector of the same model. In this study, the spray characteristics of the two injectors were compared by performing an injection quantity measurement and a spray visualization experiment. As a result, the used injector had a larger injection quantity, a shorter spray tip penetration, a wider spray angle and a smaller spray area than the new injector.

• Journal of ILASS-Korea
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• v.24 no.2
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• pp.73-81
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• 2019

It is expected that the introduction of real-driving emission will strengthen the exhaust emission. However, various researches have been reported that real-driving emission has been influenced by factors such as characteristics of the test routes and driving characteristics for drivers. In order to reflect this effect, European Commission applied the concept of driving dynamics to prevent deliberately driving of excessive and acceleration over RDE test. The purpose of this study is to analyze the characteristics of exhaust emissions according to real-driving test in three test routes and driving style. As a result of the test, it was confirmed that when the same driver tested real-driving test under three test routes, it depends on the driving characteristics of the route. Also, RDE-NOx for driving style was that severe driving has been about 16 times higher than normal driving in KNUT route.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.145-153
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• 2020

The purpose of this study is to compare the injection and spray characteristics of single-hole GDI injectors using injection rate and mie-scattering spray images. Five types of single-hole injectors with different nozzle hole diameters were used, and the spray rate, spray tip penetration, spray area, and spray width were analyzed. As a result, the diameter of the nozzle hole had a direct effect on the injection and spray characteristics. It was confirmed that the larger the diameter of the nozzle hole, the higher the injection quantity, the spray tip penetration, the spray area, and the spray width. In addition, it was confirmed that the near-field spray, which has little influence of ambient air, has a great correlation with the injection rate.

• Journal of ILASS-Korea
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• v.26 no.2
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• pp.96-103
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• 2021

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1^st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.170-177
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• 2020

Stoichiometric combustion in spark ignition (SI) engines has an advantage of meeting future stringent emission regulations. However, the drawback of the combustion is a lower thermal efficiency than that of lean burn. In this study, energy losses in a natural gas stoichiometric SI engine generator were analyzed to establish a strategy for improving the generating efficiency (GE). The energy losses were investigated based on dynamometer and load bank experiments. As the intake manifold pressure increased in the dynamometer experiment, the brake thermal efficiency (BTE) increased mainly due to the reduction in the pumping and mechanical losses. In the load bank experiment, the generating power and GE increased with the increased intake manifold pressure. The generating power and GE were lower than the brake power and BTE due to the cooling fan power and the losses in the generator.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.188-195
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• 2020

To meet stringent emission regulations of automotive engines, fuel injection control techniques have advanced based on reliable and fast computing prediction models. This study aims to develop a reliable lightweight prediction model of fuel injection rates using a small number of input parameters and based on simple fluid dynamic theories. The prediction model uses the geometry of the injector nozzle, needle motion data, injection conditions and the fuel properties. A commercial diesel injector and US No. 2 diesel were used as the test injector and fuel, respectively. The needle motion data were measured using X-ray phase-contrast imaging technique under various fuel injection pressures and injection pulse durations. The actual injector rate profiles were measured using an injection rate meter for the validation of the model prediction results. In the case of long injection durations with the steady-state operation, the model prediction results showed over 99 % consistency with the measurement results. However, in the case of short injection cases with the transient operation, the prediction model overestimated the injection rate that needs to be further improved.

• Journal of ILASS-Korea
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• v.26 no.1
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• pp.40-48
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• 2021

Lean combustion was applied to improve the thermal efficiency and emission in a single-cylinder, spark-ignition engine fueled with syngas. Under naturally aspirated conditions, the lean combustion significantly improved the thermal efficiency compared to the stoichiometric combustion, mainly due to the reduction in heat transfer loss. Intake air boost was applied to compensate the low power output of the lean combustion. The gross indicated power of 24.8 kW was achieved by increasing the intake pressure up to 1.6 bar at excess air ratio of 2.2. The nitrogen oxides showed near zero level, but the carbon monoxide emission was significant.