Seokyeon Im

Flow Uniformity of Catalytic Burner for Off-Gas Combustion of Molten Carbonate Fuel Cell

A catalytic combustor is a device to burn out the fuel by surface combustion that is used for the combustion of anode off-gas of molten carbonate fuel cell. By employing the catalytic combustor, the purified exhaust gas is able to be recirculated into the cathode channel for CO2 supply to improve thermal efficiency. The design of catalytic combustor depends on many parameters but the flow uniformity is particularly important during the emergency shut-down of fuel cell stack. Right before the temperature control of catalytic combustor is not yet activated, the catalytic combustor should burn out more than two times of rated amount of fuel flow rate. At the over-loaded condition, assurance of flow uniformity at the inlet of catalytic combustor can reduce the damage of catalytic burner caused by local hot zone. In this study, the flow uniformity of the catalytic combustor is investigated in two steps such as preliminary step with model combustor and main analysis step with practical 250 kW catalytic combustor. The 0.5 kW and 5 kW class combustors are applied for preliminary step. In preliminary step, the model combustor is used to determine supporting matters for the flow uniformity. Inlet direction of mixing chamber below the catalytic combustor is also examined in the preliminary step. In the main analysis step, flow uniformity of scale-up combustor has been examined with selected supporting matter and inlet direction into mixing chamber. Geometric and operating parameters are investigated. In particular, the flow rate at off-design operating condition has been examined.Copyright

Operating Characteristics of MCFC System on the Diversification of Fuel

Abstract >> The fuel cells have been investigated in the applications of marine as the high efficient and eco-friendlypower generating systems. In this study, modeling of IR Type molten carbonate fuel cell (Internal Reforming Typemolten carbonate fuel cell) has been developed to analyze the feasibility of thermal energy utilization. The modelis developed under Aspen plus and used for the study of system performances over regarding fuel types. The simulationresults show that the efficiency of MCFC system based on NG fuel is the highest. Also, it is also verified that the steam reforming is suitable as pre-reforming for diesel fuel. Key words : Molten carbonate fuel cell(용융탄산염연료전지), Steam reformer(수증기 개질), Autothermal reforming(자열 개질), Pre-reformer(예비 개질기) † Corresponding author : sangseok@cnu.ac.kr Received: 2015.03.23 in revised form: 2015.04.16 Accepted: 2015.04.30Copyright ⓒ 2015 KHNES 1. 서 론 최근 환경에 대한 문제가 전 세계적으로 대두되면서, 신재생 에너지 개발이 주목 받고 있다 . 그 중 연료전지는 신 에너지원으로, 특히 고온형 연료전지인 고체산화물 연료전지, 용융탄산염 연료전지는 높은 열효율, 높은 환경친화성 등의 장점을 가지고 있다 .

A Real Time Model of Dynamic Thermal Response for 120kW IGBT Inverter

Abstract >> As the power electronics system increases the frequency, the power loss and thermal management are paid more attention. This research presents a real time model of dissipation power with junction temperature response for 120kw IGBT inverter which is applied to the thermal management of high power IGBT inverter.Since the computational time is critical for real time simulation, look-up tables of IGBT module characteristiccurve are implemented. The power loss from IGBT provides a clue to calculate the temperature of each module of IGBT. In this study, temperature of each layer in IGBT is predicted by lumped capacitance analysis of layerswith convective heat transfer. The power loss and temperature of layers in IGBT is then communicated due to mutual dependence. In the dynamic model, PWM pulses are employed to calculation real time IGBT and diode power loss. Under Matlab/Simulink ® environment, the dynamic model is validated with experiment. Results showedthat the dynamic response of power loss is closely coupled with effective thermal management. The convective heat transfer is enough to achieve proper thermal management under guideline temperature.

Feasibility of a Solar Thermal Organic Rankine Cycle Power Plant for an Apartment Complex with Aspen Plus

In this study, a solar thermal system is designed to provide hot water and electricity for improvement of solar thermal energy availability in an apartment complex. The electricity is generated with Organic Rankine Cycle (ORC) by the solar thermal energy. R134a, R141b and R245fa are selected for operating fluid of the solar thermal ORC system. ORC with R245fa shows the best performance based on the variation of pressure. The irreversibility of component showed that the technology advance of the evaporator ensures a performance improvement. The sensitivity study results indicate that the turbine performance is most effective way to improve the performance of ORC system. An economic analysis showed that approximately 50% more income could be achieved by a solar thermal ORC system with a hot water supply. Corresponding Author, sangseok@cnu.ac.kr 2015 The Korean Society of Mechanical Engineers C

Charged air cooling with vortex tube for a common-rail diesel engine

When vehicle speed is low, it is hard for the intercooler to cool the charging air owing to a reduction of the ram air effect. The performance of the vortex tube is not only independent of the vehicle speed but it is also independent of the ambient temperature. This benefit motivates a feasibility study of the vortex tube as a replacement for the intercooler in a diesel engine. In this study, the performance of a diesel engine with an intercooler was compared with that of a diesel engine with a vortex tube. The engine experimental results showed that the brake specific fuel consumption (BSFC) improved up to 3 per cent at 1750 r/min and 25 per cent partial load. The results also showed the soot (particulate matter) from the diesel engine equipped with a conventional intercooler was reduced up to 60 per cent at 1500 r/min and 25 per cent partial load when the vortex tube was used. As the engine speed increased, the intercooling with the vortex tube showed a similar performance, except at high speed and full load. This study demonstrates that the overall performance of the vortex tube makes it appropriate as a replacement for the intercooler, but the result also shows that the design parameters of the vortex tube need to be optimized to cover the whole operating range.