• Journal of ILASS-Korea
• /
• v.25 no.4
• /
• pp.170-177
• /
• 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 Electrical Engineering and Technology
• /
• v.8 no.6
• /
• pp.1596-1604
• /
• 2013

Coordinating operation between large-scale wind power and thermal units in multiple time scale is an important problem to keep power balance, especially for the power grids mainly made up of large coal-fired units. The paper proposes a novel operation mode of multi-scale unit commitment (abbr. UC) that includes mid-term UC and day-ahead UC, which can take full advantage of insufficient flexibility and improve wind power accommodation. First, we introduce the concepts of multi-scale UC and then illustrate the benefits of introducing mid-term UC to the wind-coal intensive grid. The paper then formulates the mid-term UC model, proposes operation performance indices and validates the optimal operation mode by simulation cases. Compared with day-ahead UC only, the multi-scale UC mode could reduce the total generation cost and improve the wind power net benefit by decreasing the coal-fired units' on/off operation. The simulation results also show that the maximum total generation benefit should be pursued rather than the wind power utilization rate in wind-coal intensive system.

• Science of Emotion and Sensibility
• /
• v.18 no.3
• /
• pp.17-24
• /
• 2015

This study investigated heat generation characteristics of knitted and woven intelligent garments made of ZrC imbedded yarns through thermal manikin measurement. These emotional and intelligent thermal characteristics by thermal manikin measurement were analysed and compared with light/thermal radiation experimental results. Surface temperature of ZrC imbedded woven and knitted fabrics by light/thermal radiation measurement was $4^{\circ}C$ and $2^{\circ}C$ higher than that of regular PET control fabrics, respectively. Clo value as heat generation characteristics of ZrC imbedded woven and knitted garments with light exposure was 0.14 and 0.08 higher than that of regular PET control garments, respectively. These results were attributed to the far-infrared thermal radiation from ZrC imbedded in the core part of the intelligent bi-component filament, which was verified by far-infrared emissive power ranged between $6{\mu}m$ and $20{\mu}m$ through FT-IR experiment and by inclusion of Zr through EDS ingredient analysis. However, compressibility of ZrC imbedded woven fabric was lower than that of regular PET one, and bending rigidity was higher than that of regular one, which resulted in a little stiff tactile hand property of ZrC imbedded fabric. We found that ZrC imbedded intelligent woven and knitted fabrics were applicable to the intelligent garment as a heat generation textile material by thermal manikin measurement.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• v.y2005m4
• /
• pp.225-230
• /
• 2005

It is theoretically known that recuperator can bring a significant increase in thermal efficiency of the gas turbine unit, but it also has disadvantages such as pressure loss in the flow channel, thermal stress and increase in weight. Therefore it is necessary to consider all pros and cons of this equipment in view of economic aspects throughout its life cycle. Recuperator has been applied mostly in the power ranges of $20\sim300kW$ class industrial units but hasn't been used as a larger power generation unit except for naval applications in mid twentieth century. Present paper considered the applicability of a recuperator cycle in term of pressure loss, part load aspects for power generation purpose.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.12 no.4
• /
• pp.397-404
• /
• 2012

Thermal generation by power dissipation of the highly integrated System on Chip (SoC) device is irregularly distributed on the intra chip. It leads to thermal increment of the each thermally different region and effects on the propagation timing; consequently, the timing violation occurs due to the misestimated number of buffers. In this paper, the timing budgeting methodology considering thermal variation which contains buffer insertion with wire segmentation is proposed. Thermal aware LUT modeling for cell intrinsic delay is also proposed. Simulation results show the reduction of the worst delay after implementing thermal aware buffer insertion using by proposed wire segmentation up to 33% in contrast to the original buffer insertion. The error rates are measured by SPICE simulation results.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.136.2-136.2
• /
• 2011

In this work, we analyzed correlations between life-cycle greenhouse gas (GHG) emissions and life-cycle cost of energy resources. Energy resources studied in this paper include coal, natural gas, nuclear power, hydropower, geothermal energy, wind power, solar thermal energy, and solar photovoltaic energy, and all of them are used to generate electricity. We calculated the mean values, ranges of maximum minus minimum values, and ranges of 90% confidence interval of life-cycle GHG emissions and life-cycle cost of each energy resource. Based on the values, we plotted them in two dimensional graphs to analyze a relationship and characteristics between GHG emissions and cost. Besides, to analyze the technical maturity, the GHG emissions and the range of minimum and maximum values were compared to each other. For the electric generation, energy resources are largely inverse proportional to the GHG emission and the corresponding cost.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.2
• /
• pp.367-375
• /
• 2004

We have developed a highly efficient boiler system using the 2,600cc Diesel engine. In this system, the co-generation concept is utilized in that the electric power is produced by the generator connected to the engine, and waste heat is recovered from both the exhaust gases and the engine itself by the shell-and-tube heat exchangers. The heat exchanger connected to the engine outlet is specially designed such that it not only recovers waste heat effectively from the exhaust gases, but significantly reduces an engine noise. It is found that the total efficiency(thermal efficiency plus electric power generation efficiency) of this system reaches maximum 96.3％ which is about 15％ higher than the typical Diesel engine boiler system currently being used worldwide.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.23 no.12
• /
• pp.836-842
• /
• 2011

It has been shown that the air-conditioning system with slab cooling storage is effective in cutting peak load and utilizing nighttime electric power. The stochastic properties of internal heat generation which has great influence on the cooling load are examined in this paper. Based on the measured cooling load and electric power consumption in an office building with slab cooling storage, stochastic time series models to simulate these random processes are investigated. Furthermore, a calculated result by an optimal control method of thermal analysis taking into account the internal heat is compared with the measured cooling load.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.2147-2149
• /
• 2001

국내 한 증기터빈 발전소의 출력증감발 운전을 중앙급전 명령에 의해 가능하도록 하는 제어로직을 구현하였다. 이는 중앙급전으로부터 증감발 펄스 신호를 입력받아 발전기 출력 설정치를 변경함으로써 이루어지고, 증감되는 양은 펄스의 지속시간에 의해 이루어지며 여러 가지 운전상황에 대해 원활한 운전전환이 이루어져야 한다. 본 논문에서는 이를 구현하기 위해 제어로직 및 운전원 조작 화면의 구성을 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.10
• /
• pp.673-679
• /
• 2016

Because of the growing interest in supercritical carbon dioxide power cycle technology owing to its potential enhancement in compactness and efficiency, supercritical carbon dioxide cycles have been studied in the fields of nuclear power, concentrated solar power (CSP), and fossil fuel power generation. This study introduces the current status of the research project on the supercritical carbon dioxide power cycle by Korea Institute of Energy Research (KIER). During the first phase of the project, the un-recuperated supercritical Brayton cycle test loop was built and tested. In phase two, researchers are designing and building a supercritical carbon dioxide dual Brayton cycle, which utilizes two turbines and two recuperators. Under the simulation condition considered in this study, it was confirmed that the design parameter has an optimal value for maximizing the net power in the supercritical carbon dioxide dual cycle.