• Transactions of the Korean Society of Automotive Engineers
• /
• v.23 no.5
• /
• pp.494-501
• /
• 2015

Nowadays, many people are trying to develop eco-friendly engines such as the electric motor and the air engine because the I.C. engine cause a lot of pollutants. Nevertheless of these effort, there are few evaluation and comparison of these engines to conventionally used I.C. engines. Because of this, it is difficult to determine that the eco-friendly engines are really energy saving engines. In this paper, the efficiency of the air engine is calculated. The air engine does not cause environmental pollution problem because it uses "Compressed air". Due to the air engine operated at a low temperature and spark-free condition, this engine can be used in extreme condition for safety. Despite the many advantages of the air engine, there are few analysis on the air engine because of an air engine is low energy density.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.5
• /
• pp.851-856
• /
• 2017

Research on the edge isolation process of typical polycrystalline silicon solar cells was carried out using laser scribing equipment. The voltage-current characteristics of the solar cell before and after laser scribing were analyzed using a solar simulator. Current density and efficiency increased as the fill factor of the solar cell remained constant after the laser scribing process. The efficiency of the solar cell can be increased in a short time by the edge isolation process performed via a laser scribing process. The polycrystalline silicon solar cell was made into a series electrode, and the efficiency of the solar cell increased because the width of the solar cell was narrowed and the active region was widened by the laser scribing process.

• Journal of Hydrogen and New Energy
• /
• v.26 no.4
• /
• pp.377-385
• /
• 2015

This paper presents a thermodynamic performance analysis of regenerative organic Rankine cycle (ORC) using turbine bleeding to utilize low-grade finite thermal energy. Refrigerant R245fa was selected as the working fluid. Special attention is paid to the effects of the turbine bleeding pressure and the turbine bleed fraction on the thermodynamic performance of the system such as net power production and thermal efficiency. Results show that the thermal efficiency has an optimum value with respect to the turbine bleeding pressure and the net power production is lower than the basic ORC while the thermal efficiency is higher.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.130.2-130.2
• /
• 2011

The application of solar energy in residential building is general and natural in today. And application methods of solar thermal energy is divided in two kind of form, single evacuated tube and flat-plate form. Then in this study, the efficiency of single evacuated tube and flat-plate system is compared by total and effective area considering the time receiving the solar radiation between 24 hours and the specific time(10:00~15:00). As a result of the experiment, single evacuated tube and flat-plate collector's efficiency is varied by the quantity of solar radiation. And especially, the flat-plate system is more affected by outdoor temperature. Therefore the application of solar thermal system should be considered the solar radiation and outdoor temperature.

• Journal of the Korean Solar Energy Society
• /
• v.29 no.1
• /
• pp.64-69
• /
• 2009

This paper aims at enhancing the electric production efficiency of photovoltaic(PV) system. The electrical power of PV system is proportional to light intensity on a PV module surface. In this paper, we apply two types of systems to enhance power generation efficiency. First, of all, concentring sunlight using specular surface and one-axis tracking system which traces the sun with vertical direction are applied in this project. From this, we analyze the fixed type method and power generation efficiency.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.2B no.4
• /
• pp.214-218
• /
• 2002

In this paper, the effectiveness of three different control algorithms are thoroughly investigated via simulation and a proposed efficiency evaluation method of experimentation. Both the steady state and transient characteristics of each control algorithm along with its measured efficiency are analyzed. Finally, a novel two-mode maximum power point tracking (MPPT) control algorithm combining the constant voltage control and the incremental conduction (IncCond) methods is proposed to improve the efficiency of the 3KW PV power generation system at different insolation conditions. Experimental results show that the proposed two-mode MPPT control provides excellent performance at less than 30% insolation intensity, covering the whole insolation area without additional hardware circuitry.

• Journal of IKEEE
• /
• v.23 no.2
• /
• pp.350-357
• /
• 2019

We analyzed the system efficiency of small solar power plants with 80% of total solar power plants. The data of the solar power plant with installed capacity of 100kW was collected and the correlation of the ESS efficiency according to the capacity of the PCS and the battery of each power plant was deduced. As a result, the higher the C-rate value affecting the discharge rate of the battery, The discharge efficiency of the plasma display panel is increased.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.13 no.4
• /
• pp.1-7
• /
• 2017

The energy slab is a ground coupled heat exchanger equipped in building slab structures, which represents a layout similar to the horizontal ground heat exchanger (GHEX). The energy slab is installed as one component of the floor slab layers in order to utilize the underground structure as a hybrid energy structure. However, as the energy slab is horizontally arranged, its thermal performance is inevitably less than the conventional vertical GHEXs. Therefore, stainless steel (STS) pipes are alternatively considered as a heat exchanger instead of high density polyethylene (HDPE) pipes in order to enhance thermal performance of GHEXs. Moreover, not only a floor slab but also a wall slab can be utilized as a heat-exchangeable energy slab in order to maximize the use of underground space effectively. In this paper, four field-scale energy slabs were constructed in a test bed, which consist of the STS and HDPE pipe, and a series of thermal response tests (TRTs) was conducted to evaluate relative heat exchange efficiency per unit pipe length according to the pipe material and the configuration of energy slabs. The energy slab equipped with the STS pipe shows higher thermal performance than the energy slab with the HDPE pipe. In addition, thermal performance of the wall-type energy slab is almost equivalent to the floor-type energy slab.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.12
• /
• pp.176-183
• /
• 2009

Distributed generation(DG) of combined cooling, heat, and power(CCHP)has been gaining momentum in recent year as efficient, secure alternative for meeting increasing energy demands. This paper presents the energy performance of microturbine CCHP system equipped with an absorption chiller by modelling it in hospital building. The orders of study were as following. 1)The list and schedule of energy consumption equipment in hospital were examined such as heating and cooling machine, light etc. 2) Annual report of energy usage and monitoring data were examined as heating, cooling, DHW, lighting, etc. 3) The weather data in 2007 was used for simulation and was arranged by meteorological office data in Daejeon. 4) Reference simulation model was built by comparison of real energy consumption and simulation result by TRNSYS and ESP-r. The energy consumption pattern of building were analyzed by simulation model and energy reduction rate were calculated over the cogeneration. As a result of this study, power generation efficiency of turbine was about 30[%] after installing micro gas turbine and lighting energy as well as total electricity consumption can be reduced by 40[%]. If electricity energy and waste heat in turbine are used, 56[%] of heating energy and 67[%] of cooling energy can be reduced respectively, and total system efficiency can be increased up to 70[%].

• 에너지협의회보
• /
• s.17
• /
• pp.4-10
• /
• 1990