• 신재생에너지
• /
• 제19권4호
• /
• pp.61-71
• /
• 2023

The necessity of energy utilization using livestock manure has been proposed with the decrease in domestic agricultural land. Livestock manure solid fuel has been investigated as a promising energy resource owing to its convenient storage and use in agricultural and livestock fields. Additional electricity production is possible through the integration of a biomass combustion boiler with the organic Rankine cycle (ORC). In this study, a mathematical system model of the cattle manure solid fuel boiler integrated with the ORC was developed to analyze the components' performance under variable operating conditions. A sensitivity analysis was conducted to confirm the electrical efficiency of the ORC turbine and the applicability of this system. The minimum required waste heat recovery rate was derived considering the system marginal price and levelized cost of electricity of the ORC. The simulation results showed that, in Korea, more than 77.98% of waste heat recovery and utilization in ORC turbines is required to achieve economic feasibility through ORC application.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 A
• /
• pp.355-357
• /
• 1996

With the wide-spread use of rectifier in electronic equipments, such problems as electronic components failures or equipment disorders have been occurred due to current harmonics. To overcome these problems, power factor correction circuits employing boost converter have been used. The switching stress of boost converter can be reduced by snubber circuit. Recently, research activities in snubber circuits have been directed to energy recovery snubber for improving the efficiency of power converter. In this study, a new passive snubber circuit which can recover trapped snubber energy without added control is proposed for boost converter The control of boost converter with proposed snubber is the same as the conventional one. In addition, the energy recovery circuit can be implemented with a few passive components. The circuit operation is confirmed through simulation.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 추계학술대회 논문집
• /
• pp.159-163
• /
• 2001

A new and high-efficient energy-recovery circuit is proposed to drive a Plasma display panel (PDP) and compared with the conventional circuit. The Proposed circuit uses only two inductors and no auxiliary circuit to recover the energy stored in the equivalent intrinsic capacitance of Plow DP so that it feartures a very simple structure, small volume, fewer power devices. production cost and high efficiency. Besides, the light emitted from PDP is very stable and uniform. It is suitable for wall-hanging color TVs. The proposed circuit, operating at 200kHz, is verified to be applicable on a 42-inch PDP by an experiment.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2007년도 추계종합학술대회
• /
• pp.250-253
• /
• 2007

본 논문에서는 플라즈마 디스플레이 패널의 구동시 발생되는 전력손실을 최소화시키기 위한 에너지 회수기능을 가지는 새로운 서스테인 구동회로를 제안한다. 제안된 회로는 패널의 등가 커패시턴스와 외부 인덕터의 직렬공진을 이용하여 패널에 에너지를 공급/회수하게 된다. 제안된 에너지 회수 회로는 기존에 널리 이용되는 에너지 회수와 비교하여 저가형 구조로 구성이 가능하며 우수한 에너지 회수 성능을 가진다. 7.5인치 AC-PDP를 이용한 실험을 통해 제안된 회로의 타당성을 검증한다.

• 한국산학기술학회논문지
• /
• 제14권6호
• /
• pp.2588-2595
• /
• 2013

기존의 유압식 엘리베이터에서 엘리베이터 카의 하강행정 동안 손실 되는 유압 에너지를 회수하여 재사용하기 위하여 개발한 유압식 엘리베이터용 하이브리드 형 에너지 저감 장치에 대한 성능 특성에 관하여 연구하였다. 회수된 에너지는 축전지에 저장하여 재사용할 수 있도록 구성되어 있으며, 엘리베이터의 구동 조건에 따른 에너지 저감장치의 출력 특성, 효율 및 에너지 회수율 등에 관하여 실험을 통하여 규명하고자 하였다. 본 연구의 결과들은 하강행정 동안 버려지는 에너지의 회수율이 최대 약 54%로 에너지 저감 장치의 압력, 유량, 출력 전압과 전류, 효율 및 에너지 회수율 등과 같은 성능 특성들이 안정적이고 양호하다는 것을 보여주고 있으며, 본 연구를 통하여 유압식 엘리베이터의 에너지 저감 장치를 통하여 하강행정 동안 회수된 에너지를 재사용하데 매우 유용하며, 상용화 가능성이 충분하다는 것을 확인하였다.

• Environmental Engineering Research
• /
• 제24권2호
• /
• pp.347-353
• /
• 2019

Although membrane distillation (MD) has great promise for desalination of saline water sources, it is crucial to improve its thermal efficiency to reduce the operating cost. Accordingly, this study intended to examine the thermal energy efficiency of MD modules in a pilot scale system. Two different modules of hollow fiber membranes were compared in direct contact MD mode. One of them was made of polypropylene with the effective membrane area of $2.6m^2$ and the other was made of polyvinylidene fluoride with the effective membrane area of $7.6m^2$. The influence of operation parameters, including the temperatures of feed and distillate, feed flow rate, and distillate flow rate on the flux, recovery, and performance ratio (PR), was investigated. Results showed that the two MD membranes showed different flux and PR values even under similar conditions. Moreover, both flow rate and temperature difference between feed and distillate significantly affect the PR values. These results suggest that the operating conditions for MD should be determined by considering the module properties.

• Journal of Power Electronics
• /
• 제15권5호
• /
• pp.1305-1317
• /
• 2015

Distributed generation systems (DGSs) have been getting more and more attention in terms of renewable energy use and new generation technologies in the past decades. The self-excited induction generator (SEIG) occupies an important role in the area of energy conversion due to its low cost, robustness and simple control. Unlike synchronous generators, the SEIG has to absorb capacitive reactive power from the outer device aiming to stabilize the terminal voltage at load changes. This paper presents a novel static VAR compensator (SVC) called a magnetic energy recovery switch (MERS) to serve as a voltage controller in SEIG powered DGSs. In addition, many small scale SEIGs, instead of a single large one, are applied and devoted to promote the generation efficiency. To begin with, an expandable mathematic model based on a d-q equivalent circuit is created for parallel SEIGs. The control method of the MERS is further improved with the objective of broadening its operating range and restraining current harmonics by parameter optimization. A hybrid control strategy is developed by taking both of the stand-alone and grid-connected modes into consideration. Then simulation and experiments are carried out in the case of single and double SEIG(s) generation. Finally, the measurement results verify that the proposed DGS with SVC-MERS achieves a better stability and higher feasibility. The major advantages of the mentioned variable reactive power supplier, when compared to the STATCOM, include the adoption of a small DC capacitor, line frequency switching, simple control and less loss.

• 전기학회논문지
• /
• 제66권8호
• /
• pp.1207-1214
• /
• 2017

In the case of frequent braking, when driving downhill or long distance, conventional brakes using friction are problematic in braking safety due to brake rupture and fading phenomenon. Therefore auxiliary brakes is essential for heavy vehicles. And several research has been actively conducted to improve energy efficiency by regenerating mechanical energy into electric energy when the vehicles brake. In this paper, a voltage control method is utilized to recover the electric energy generated in the electromagnetic retarder instead of the eddy current. To regenerate the braking energy into the electrical energy, a resonant L-C circuit is configured in the retarder. The retarder can be modeled as self-excited induction generator due to its operating principle. The driving conditions according to the retarder's parameters are made into 3-D maps. Also, the voltage of the resonant circuit changing depending on the driving pulse applied to the FET was analyzed. For the control of this voltage, we proposed an algorithm using the PI controller. The controlled voltage is converted by a 3-phase AC/DC converter and then charged to a battery inside the heavy vehicles through a DC/DC converter. Electromagnetic retarder and its controller are validated using Matlab Simulink. We also demonstrate the voltage controller through the actual M-G set experiment.

• 한국태양에너지학회 논문집
• /
• 제37권5호
• /
• pp.27-37
• /
• 2017

In this study, an artificial solar simulator composed of a 2.5 kW Xe-Arc lamp and mirror reflector was used to carry out the solar thermal two step thermochemical water decomposition cycle which can produce high efficiency continuous hydrogen production. Through various operating conditions, the change of hydrogen production due to the possibility of a dual-zone reactor and heat recovery were experimentally analyzed. Based on the reaction temperature of Thermal-Reduction step and Water-Decomposition step at $1,400^{\circ}C$ and $1,000^{\circ}C$ respectively, the hydrogen production decreased by 23.2% under the power off condition, and as a result of experiments using heat recovery technology, the hydrogen production increased by 33.8%. Therefore, when a thermochemical two-step water decomposition cycle is conducted using a dual-zone reactor with heat recovery, it is expected that the cycle can be operated twice over a certain period of time and the hydrogen production amount is increased by at least 53.5% compared to a single reactor.

• 한국수소및신에너지학회논문집
• /
• 제20권5호
• /
• pp.416-423
• /
• 2009

High-temperature steam electrolysis (HTSE) using solid oxide cell is a challenging method for highly efficient large-scale hydrogen production as a reversible process of solid oxide fuel cell (SOFC). The overall efficiency of the HTSE hydrogen and synthesis gas production system was analyzed thermo-electrochemically. A thermo-electrochemical model for the hydrogen and synthesis gas production system with solid oxide electrolysis cell (SOEC) and very high temperature gas-cooled reactor (VHTR) was established. Sensitivity analyses with regard to the system were performed to investigate the quantitative effects of key parameters on the overall efficiency of the production system. The overall efficiency with SOEC and VHTR was expected to reach a maximum of 58% for the hydrogen production system and to 62% for synthesis gas production system by improving electrical efficiency, steam utilization rate, waste heat recovery rate, electrolysis efficiency, and thermal efficiency. Therefore, overall efficiency of the synthesis production system has higher efficiency than that of the hydrogen production system.