• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.233-239
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• 2014

The accurate engine output is basically one of important factors for the analysis of engine performance. Nowadays in-cylinder pressure analyzer in internal combustion engine is also an indispensable tool for engine research and development, environment regulation and maintenance of engine. The combustion analysis is desperately needed in order to induce a correct judgment on the condition of the engine and suggest the specific ways to improvement as well as the correct engine output. And these tool is advantageous to reduce fuel consumption and maintenance of the engine. In this study, using the developed measuring kit, combustion analysis of marine generator engine which was adapted as test engine was carried out. It was verified that the good operation condition of the engine as well as contributing to fuel savings by checking and readjusting accurately the irregular combustion of the test engine were accomplished. From the results all above, it was recognized that the measuring kit by new method for engine output was developed and verified for its utilities.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.3
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• pp.232-242
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• 2005

It has been recognized that solar water heating systems are economically inferior to conventional gas water-heaters and boilers using light oil as fuel in spite of having practical possibilities among other alternative energy facilities in Korea. The solar system, however, should be revaluated due to the sharp rise of oil prices recently. We have calculated the energy amount and cost through a series of research projects for the system by experiment and simulation, which lead to analyzing reliable life cycle costs. For the economic analysis, the gas water-heater and light oil boiler were taken as base cases while the solar systems implemented with these facilities were compared as alternatives. As a result, the solar system using the light oil as an auxiliary fuel surpassed the light oil boiler in economics. And a $50\%$ government subsidy for the initial cost is needed to maintain competitiveness with the gas hot-water heater. With this support, the simple payback period of the system can approach 12.8 years under $20\%$ additional curtailment of expenditure.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.6
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• pp.83-90
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• 2017

Performance analysis of the turboshaft engines for combined rotorcraft was executed. A tip jet and a ducted fan aircraft were selected for combined rotorcraft application. Gasturb 12 software was used for turboshaft engine performance analysis. In the results, maximum required power for the tip jet engine is about 1,600 hp class and maximum required power for the ducted fan engine is about 1,000 hp class at the required aircraft mission. This is due to the additional power of the auxiliary compressor to get a bleed air mass flow rate for the tip jet operation. At the same time, fuel consumption of the tip jet aircraft is 2.8 times larger than ducted fan case. Therefore ducted fan type aircraft is more efficient than tip jet aircraft in terms of fuel economy.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.800-803
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• 2007

Gasification has been regarded as a core technology in dealing with environmental pollutants and in obtaining higher efficiency for power generation. Among several ways in utilizing produced syngas from gasification, power generation would be the most prominent application. Syngas from coal was applied to the readily available LPG engine from automobiles. Main purpose was to identify the combustion characteristics in the modified gas engine when using syngas of low heating value and to test the modification optionsin the LPG gas engine. Gas engine rpm and the corresponding flue gas composition were measured for each syngas input condition. Results showed that even with syngas at the heating value of $1300{\sim}1800$ kcal/$Nm^3$ corresponding to the $6{\sim}7%$ of LPG heating value, gas engine operated successfully only with the problems of high CO and oxygen concentrations in the flue gas.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.8-14
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• 2014

Pulverized coal (PC) has become an important auxiliary fuel in the iron and steel industry since the technique of pulverized coal injection (PCI) was developed for iron making. The combustion efficiencies of pulverized coal in blowpipes and tuyeres under various operational conditions are numerically predicted to determine the performance levels with regard to different locations of the nozzles in a blast furnace. A variety of parameters, including the pulverized coal quantities, oxygen amounts, inlet temperatures of the tuyeres, and the mass flow rate of coal carrier gas are taken into consideration. Also, in order to develop greater efficiency than those of existing coal injection systems, this study applies a flame measurement system using a charge-coupled device (CCD) camera and a frame grabber. It uses auto sampling algorithms from the flame shape information to determine the device for the optimal location control for PCI. This study finds further improvements of the blast furnace performance via the control of the PCI locations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.9
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• pp.704-711
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• 2008

Integrated gasification combined cycle (IGCC) is an environment friendly method of using coal. Several commercial IGCC plants have been built worldwide during the past decade, and a domestic development project has also been launched recently. Operation and performance characteristics of a gas turbine in the IGCC plant deviates from those of original gas turbines due to several factors such as increased amount of fuel supply and integration with other components. In this study, performance of a gas turbine in the IGCC plant is analyzed considering its integration with the air separation unit (ASU). Influence of the degree of integration (split of air supplies to ASU from the auxiliary compressor and the gas turbine compressor) on the system performance is investigated. In addition, effect of modulating nitrogen return flow from the gasifier to the gas turbine on the operating characteristics of the gas turbine is examined.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3163-3168
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• 2008

Pulverized coal (PC) has become an important auxiliary fuel in the iron and steel industry since the technique of pulverized coal injection (PCI) system was developed for iron making. Combustion efficiencies of pulverized coal in blowpipes and tuyeres under various operational are numerically predicted to recognize the performance with the locations of nozzles in a blast furnace. A variety of parameters including the pulverized coal quantities, oxygen amounts, inlet temperature of the tuyeres and mass flow rate of coal carrier gas are taken into consideration. Also In order to develop more efficient than existing coal injection system, this study applies a flame measurement system using a charge couple device (CCD) camera and frame grabber. And it has used algorithms of auto sampling from flame shape information and composed the device for location control of PCI. This study find to further improve the blast furnace performance by the control of PCI locations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.135-144
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• 2021

In this study, we investigated the characteristics of the process of hydrogen production using boil-of gas (BOG) generated from an LNG-fueled ship and the application of hydrogen fuel cell systems as auxiliary engines. In this study, the BOG steam reformer process was designed using the UniSim R410 program, and the reformer outlet temperature, pressure, and the fraction and consumption of the product according to the steam/carbon ratio (SCR) were calculated. According to the study, the conversion rate of methane was 100 % when the temperature of the reformer was 890 ℃, and maximum hydrogen production was observed. In addition, the lower the pressure, the higher is the reaction activity. However, higher temperatures have led to a decrease in hydrogen production owing to the preponderance of adverse reactions and increased amounts of water and carbon dioxide. As SCR increased, hydrogen production increased, but the required energy consumption also increased proportionally. Although the hydrogen fraction was the highest when the SCR was 1.8, it was confirmed that the optimal operation range was for SCR to operate at 3 to prevent cocking. In addition, the lower the pressure, the higher is the amount of carbon dioxide generated. Furthermore, 42.5 % of the LNG cold energy based on carbon dioxide generation was required for cooling and liquefaction.

• Journal of Power Electronics
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• v.17 no.2
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• pp.490-500
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• 2017

Fuel cell (FC) is a promising power supply in electric vehicles (EV); however, it has poor dynamic performance and short service life. To address these shortcomings, a super capacitor (SC) is adopted as an auxiliary power supply. In this study, the frequency decoupling control method is used in electric vehicle energy system. High-frequency and low-frequency demand power is provided by SC and FC, respectively, which makes full use of two power supplies. Simultaneously, the energy system still has rapidity and reliability. The distributed power system (DPS) of EV requires DC-DC converters to achieve the desired voltage. The stability of cascaded converters must be assessed. Impedance-based methods are effective in the stability analysis of DPS. In this study, closed-loop impedances of interleaved half-bridge DC-DC converter and phase-shifted full-bridge DC-DC converter based on the frequency decoupling control method are derived. The closed-loop impedance of an inverter for permanent magnet synchronous motor based on space vector modulation control method is also derived. An improved Middlebrook criterion is used to assess and adjust the stability of the energy system. A theoretical analysis and simulation test are provided to demonstrate the feasibility of the energy management system and the control method.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.339-344
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• 2005

A PEMFC system model for FCEV was constructed and simulated numerically to examine the heat/water flow of the system and air/fuel humidification process for various operation conditions (ambient pressure /temperature/humidity, operating temperature, power load). We modeled PEMFC stack which can generate maximum electricity of about 80 kW. This stack consists of 400 unit cells and each unit cell has $250cm^2$ reacting area. Uniform current density and uniform operating voltage per each cell was assumed. The results show the flow characteristics of heat and water at each component of PEMFC system in macro-scale. The capacity shortage of the radiator occurred when the ambient was hot $(over\;40^{\circ}C)$ and power level was high (over 50 kW). In spite of some heat release by evaporation of water in stack, heat unbalance reached to 20kW approximately in such a severe operating condition. This heat unbalance could be recovered by auxiliary radiators or high speed cooling fan with additional cost. In cold environment, the capacity of radiator exceeded the net heat generation to be released, which may cause a problem to drop the operating temperature of stack. We dealt with this problem by regulating mass flow rate of coolant and radiator fan speed. Finally, water balance was not easily broken when we retrieved condensed and/or unused water.