• Fire Science and Engineering
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• v.16 no.4
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• pp.33-43
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• 2002

To analyze the effect of fire plume on the characteristics of air flow and $CO_2$, extinguishant transfer when extinguishant is injected into a closed space similar to a marine engine room with fire plume, a numerical simulation on a space was performed. Flow fields and $CO_2$, concentration fields are calculated according with the variation of the location of nozzles. In all cases excepting the case of all nozzles located in the right side of ceiling, an counterclockwise & clockwise recirculation flow was found in the region of the right and left side of the nozzle on the second floor and such a recirculation flow greatly affected mass transfer and the diffusion process of $CO_2$, extinguishant. In the region of the first floor with fire plume, the diffusion process of $CO_2$, extinguishant was in agreement with the extension process of recirculation flow. It is considered that the result of this study can be useful to designing the arrangement of nozzles for the $CO_2$ fire fighting equipments in a marine engine room.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.825-828
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• 2009

고형원료인 폐기물의 감량화 및 자원화 기술 중 가장 대표적인 기술로 폐기물의 소각(incineration)기술과 가스화(gasification)용융기술을 들 수 있다. 폐기물 가스화 기술은 폐기물 내의 탄소, 수소 성분을 가스화하여 CO, $H_2$가 주성분인 합성가스(synthesis gas, syngas)로 전환하여 불연물은 용융되어 환경적으로 무해한 슬래그로 회수하는 기술이다. 폐기물 가스화 용융 시스템으로 발생된 합성가스를 재순환하여 사용하는 합성가스 재순환시스템을 통해 가스화에 필요한 열을 시스템 내에서 대체하여 사용하는 기술개발은 폐기물 가스화 용융기술의 경제성을 높일 수 있다. 본 연구에서는 고형 폐기물 가스화반응에 의해 발생되는 합성가스를 재순환하여 폐기물 가스화 용융 시스템내의 자체 에너지원으로 활용할 수 있도록 하는 합성가스 재순환 시스템 및 버너의 운전특성을 고찰하였다. 합성가스의 재순환 장치에서의 운전 압력 제어 및 유량제어를 통해서 안정적인 합성가스 재순환 성능과 재순환버너의 연소 성능을 유지할 수 있었다. 합성가스 재순환버너에 의한 16,800 $kcal/Nm^3$ 조건 및 33,600 $kcal/Nm^3$ 조건에서 운전시에도 가스화기의 운전온도는 안정적으로 유지됨에 따라 생산된 합성가스의 가스화기 보조연료 대체 및 에너지절감이 가능한 것으로 판단된다.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.37-43
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• 2003

The exhaust gas recirculation (EGR) is needed for one of various strategies to reduce NOx emission. But to get the proper EGR rate, the intake and exhaust system become complicated, also application of EGR system is difficult because of the penalty in fuel consumption and the increase in particulate matter. This study is focused on the development of EGR valve using the electrical method. The effects of EGR on the characteristics of NOx, CO, CO2 emissions and particulate mater have been investigated using small-displacement size 0.8-liters engine of diesel passenger car operating at several loads and speeds. After the analysis and comparison between conventional E-EGR valve and developed E-EGR valve performance by test bench, the estimation of vehicle application was executed through the EGR map and CVS-75 test result measured on the chassis dynamometer.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.329-334
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• 2009

An oxy-fuel boiler has been developed to capture $CO_2$ from the exhaust gas. FGR (flue gas recirculation) is adopted to be compliant with the retrofit scenario. Numerical simulations have been performed to study the detailed physics inside the combustion chamber of the boiler. The temperature field obtained from the simulation agrees with the flame image from the experiment. The FGR combustion yields similar heat transfer characteristics with the conventional air combustion while the flame is formed further downstream in case of the FGR combustion.

• Journal of the Korea Concrete Institute
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• v.29 no.4
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• pp.379-387
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• 2017

The objective of this study is to develop sustainable PVA fiber-reinforced cementitious composites (FRCCs) that could exhibit comparable strength level to normal PVA FRCCs with no recycled materials. To evaluate mechanical properties of the FRCCs, compressive, flexural and direct tensile tests were conducted. In addition to the test, to calculate amount of carbon dioxide ($CO_2$) emission at the stage of manufacturing the FRCCs, life cycle inventory data base (LCI DB) were referenced from domestic and Japan. From the test results, the mechanical properties such as compressive, flexural and direct tensile strengths were decreased as the replacement ratio of recycled materials increased. And it was determined that the amount of $CO_2$ emission was reduced for the specimens with higher water-binder ratio (W/B) and replacement ratios. It was also found that binder intensity ($B_i$) value was higher as replacement ratio of fly ash (FA) increased. This result means that larger amount of FA is need to deliver one unit of a given performance indicator (1 MPa of strength) of FRCCs compared to that of ordinary portland cement (OPC). As a result, it could be concluded that FRCCs with W/B 45% replaced by FA 25% and recycled sand (RS) 25% is desirable for both target performance and $CO_2$ emission.

• Magazine of RCR
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• v.4 no.2
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• pp.7-17
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• 2009

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2006.05a
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• pp.412-419
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• 2006

An Experimental study was conducted on $CO_{2}$ recycle combustion heating system using pure oxygen instead of conventional air as an oxidant, which is thereby producing a flue gas of mostly $CO_{2}$ and water vapor($H_{2}O$ and water vapor($H_{2}O$) and resulting in higher $CO_{2}$ concentration. The advantages of the system are not only the ability to control high temperatures characteristic of oxygen combustion with recycling $CO_{2}$ but also the possibility to reduce NOx emission in the flue gas. A small scale industrial reheating furnace simulator and specially designed variable flame burner were used to characterize the $CO_{2}$ recycle oxy-fuel combustion, such as the variations of furnace pressure, temperature and composition in the flue gas during recycle. It was found that $CO_{2}$ concentration in the flue gas was about 80% without $CO_{2}$recycle. The furnace temperature and pressure and pressure were decreased due to recycle and the NOx emission was also reduced to maintain under 100ppm.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.647-653
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• 2007

The ultimate objective of this study is to develop a reliable oxygen-enriched combustion techniques especially for the case of the flue gas recycling in order to reduce the $CO_2$ emissions from practical industrial boilers. To this end a systematic numerical investigation has been performed, as a first step, for the resolution of the combusting flame characteristics of lab-scale LNG combustor. One of the important parameters considered in this study is the level of flue gas recycling calculated in oxygen enriched environment. As a summary of flame characteristics, for the condition of 100% pure $O_2$ as oxidizer without any flue gas recycling, the flame appears as long and thin laminar-like shape with relatively high flame temperature. The feature of high peak of flame temperature is explained by the absence of dilution and heat loss effects due to the presence of $N_2$ inert gas. The same reasoning is also applicable to the laminarized thin flame one, which is attributed to the decrease of the turbulent mixing. These results are physically acceptable and consistent and further generally in good agreement with experimental results appeared in open literature. As the level of $CO_2$ recycling increases in the mixture of $O_2/CO_2$, the peak flame temperature moves near the burner region due to the enhanced turbulent mixing by the increased amount of flow rate of oxidizer stream. However, as might be expected, the flue gas temperature decreases due to presence of $CO_2$ gas together with the inherent feature of large specific heat of this gas. If the recycling ratio more than 80%, gas temperatures drop so significantly that a steady combustion flame can no longer sustain within the furnace. However, combustion in the condition of 30% $O_2/70% $ $CO_2$ can produce similar gas temperature profiles to those of conventional combustion in air oxidizer. An indepth analyses have been made for the change of flame characteristics in the aspect of turbulent intensity and heat balance.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.60-67
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• 2021

This study presented techno-economic analysis of a 500 MWe oxy-coal power plant with CO2 capture. The power plant included a circulating fluidized-bed (CFB), ultra-supercritical steam turbine, flue gas conditioning (FGC), air separation unit (ASU), and CO2 processing unit (CPU). The dry flue gas recirculation (FGR) was used to control the combustion temperature of CFB. One FGR heat exchanger, one heat exchanger for N2 stream exiting ASU, and a heat recovery from CPU compressor were considered to enhance heat efficiency. The decrease in the temperature difference (ΔT) of the FGR heat exchanger that means the increase in heat recovery from flue gas enhanced the electricity and exergy efficiencies. The annual cost including the FGR heat exchanger and FGC cooling water was minimized at ΔT = 10 ℃, where the electricity efficiency, total capital cost, total production cost, and return on investment were 39%, 1371 M$, 90 M$, and 7%/y, respectively.

• Journal of the Korean GEO-environmental Society
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• v.6 no.1
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• pp.5-13
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• 2005

The conventional settlement prediction method is not appropriate to model landfill settlement because it is very complex phenomenon. Biodegradation needs to be considered for long-term settlement since landfills are comprised of various organic materials and soils. As organic materials are decomposed, they directly influences on settlement producing LFG(Landfill Gas). Therefore, mathematical settlement prediction model is proposed based on the generated gas volume. As one of stabilization methods, leachate recycling system is adopted to model tests. Two model tests; one is leachate recycled, the other is non-recycled, are componented with proposed model and analysed regarding gas generation and settlement. The proposed mathematical model requires correction coefficients of 1.4 and 1.7 for non-recycled model and recycled, respectively. The recycled model showed 22% increase of long-term settlement more than the non-recycled model.