• Title, Summary, Keyword: charging system

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Heat Transfer Characteristics of the Spherical Capsule Storage System Using Paraffins

  • Cho, Keum-Nam;Choi, S. H.
    • International Journal of Air-Conditioning and Refrigeration
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    • v.6
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    • pp.113-123
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    • 1998
  • The present study is to investigate the effect of experimental parameters on the heat transfer characteristics of a spherical capsule storage system using paraffins. N-Tetradecane and mixture of n-Tetradecane 40% and n-Hexadecane 60% were used as paraffins. Water with inorganic material was also tested for the comparison. The experimental parameters were varied for the Reynolds number from 8 to 16 and for the inlet temperature from -7 to 2$^{\circ}C$. Measured local temperatures of spherical capsules in the storage tank were utilized to calculate charging and discharging times, dimensionless thermal storage amount, and the average heat transfer coefficients in the tank. Local charging and discharging times in the storage tank were significantly different. The effect of inlet temperature on charging time was larger than that on discharging time, but the effect of Reynolds number on charging time was smaller than that on discharging time. Charging time of paraffins was faster by 11~72% than that of water with inorganic material, but little difference of discharging time was found among them. The effect of Reynolds number on the dimensionless thermal storage was less during charging process and more during discharging process than the effect of inlet temperature. The effect of the inlet temperature and the Reynolds number on the average heat transfer coefficient of the storage tank was stronger during discharging process than during charging process. The average heat transfer coefficients of the spherical capsule system using paraffins were larger by 40% than those using water.

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Charging Characteristics of Electrostatic Sprayer Applied Square Pulse (구형파 펄스를 인가한 정전분무 장치의 대전량 특성)

  • 박승록;문재덕
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.12
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    • pp.573-578
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    • 2003
  • In this study, new type of induction charging system for electrostatic spraying was manufactured and proposed to improve the electrical safety and charging efficiency. And parameters of proposed system to generate the maximum deposition current with electrical safety were selected and investigated. The selected parameters were frequency of square pulse and thickness of insulation material, outer diameter of device and thickness and positions of electrode. Charging quantity of water drop was measured by deposition current detected from sensing plate indirectly. The maximum deposition current for each parameter were 3.5[uA] at the frequency of 15[kHz] and thickness of 0.25[mm] insulating layer. And maximum deposition currents were 2.8[uA] and 3.0[uA] at 25[mm] outer diameter of charging device and 0.25[mm] thickness of electrode each. Effects of electrode position from spraying nozzle on deposition current was a little.

A Case of Underwater Blasting Performance Using a Structural Underwater Charging System (수중발파용 구조체를 이용한 수중발파 시공사례)

  • Kim, Young- Keun;Kim, Seung-Kon
    • Explosives and Blasting
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    • v.36 no.2
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    • pp.27-35
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    • 2018
  • This study introduces a suggested underwater blasting method in contrast with conventional underwater blasting methods which adopt the drilling and charging procedures by divers. A structural underwater charging system makes it possible to drill into underwater bedrock and charge explosives on the deck of barge ship. The applicability and effectiveness of the suggested method was experimentally approved by comparing with a kind of underwater charging system as a conventional underwater blasting method.

Effects of Charging Conditions on Evaporating Temperature for Diffusion Absorption Refrigerator (확산형 흡수식 냉장고에서 작동매체 충진조건이 증발온도에 미치는 영향)

  • 김선창;김영률;백종현;박승상
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.10
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    • pp.828-834
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    • 2003
  • A diffusion absorption refrigerator is a heat-generated refrigeration system. It uses a three-component working fluid consisting of the refrigerant (ammonia), the absorbent (water) and the auxiliary gas (hydrogen or helium). In this study, experimental investigations have been carried out to examine the effects of charging conditions of working fluids on the evaporating temperature for diffusion absorption refrigerator. Experimental parameters considered in the present experiments are charging concentration, solution charge and system pressure determined by auxiliary gas charged. As a result, in the charging condition of 35% of concentration and 20 kg$_{f}$cm$^2$ of system pressure, the system has the lowest evaporating temperature. It was found that there exists a minimum value of solution charge for the operation of diffusion absorption refrigerator.r.

The Study of Engine Output and Emission Characteristics according to Air Fuel Ratio far a Supercharged LPLi Engine (과급 LPLi 엔진의 공연비 변화에 따른 출력성능 및 배기특성에 관한 연구)

  • 류재덕;윤용원;이기형;이창식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.4
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    • pp.77-84
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    • 2002
  • For the purpose of obtaining a fundamental data which is needed to develope the port injection type charged LPLi engine system, we manufactured intake port injection system of liquid charging LPG and modified heavy duty single cylinder LPLi engine from heavy duty diesel engine. Engine output and emission characteristics were analyzed under variable air/fuel ratio and charging pressure. Since LPG is consisted of propane and butane, we investigated combustion characteristics using this two kinds of fuel. From the result of charging engine performance test, engine torque increase about 30% ∼ 40% with 0.3bar charging pressure. In low speed condition, as charging pressure increase, combustion stability improve ill lean bum condition, but, in high speed condition, combustion stability make worse in lean bum condition. We know that engine output decreased rapidly from the condition of air excess ratio 1.3. In addition, we measured emission characteristics under the lean bum and charging condition. From this experiment, we found that CO emission is out of the question in the range from stiochiometric to lean burn and charging condition, but charging pressure has influence on HC emission.

Improvement of Step-charging Characteristic for Ni-MH Battery by Selective Cut-off Method (선택적 충전단계절환에 의한 Ni-MH 전지의 계단충전 특성 개선)

  • 안재영;강신영;김광헌;임영철
    • The Transactions of the Korean Institute of Power Electronics
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    • v.3 no.4
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    • pp.273-279
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    • 1998
  • In this paper, the proposed charging system consists of step charging mode and time-sharing equalization charging mode. As $\Delta$V=O point is detected, the proposed cut-off method will selectively cut off the only battery to reach the $\Delta$V=O point, preventing serial-connected batteries from undercharging. In the start of each step, the equalization charging mode is performed to reduce the capacity difference among the batteries. Though it is added to simple circuit for selective cut-off, comparing with recently used step-charging method, this system can improve the life cycle of battery and charging efficiency, and be also very effective for preventing the batteries from overcharging and undercharging.

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Development of the Gas Charging Simulator for Reaction Control System of KSLV-I (KSLV-I RCS 충전모사 시스템 개발)

  • Jeon, Sang-Woon;Jung, Seul;Kim, Ji-Hun
    • Aerospace Engineering and Technology
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    • v.8 no.2
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    • pp.122-126
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    • 2009
  • KSLV(Korea Space Launch Vehicle)-I is designed as a launch vehicle to enter a 100 kg-class satellite to the LEO(Low-Earth Orbit). Attitude angles of the upper-stage, including roll, pitch and yaw are controlled by cold gas thruster system using nitrogen gas. To verify the flow rate of the gas charging system and to prepare a nitrogen gas charging scenario, the development of a gas charging simulator for RCS(Reaction Control System) is required. This paper describes the orifice design, development, and test of the gas charging simulator for RCS of KSLV-I.

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An Analysis on the Stability of the Electric Vehicles Connected Power System According to Charging Cost with Price Elasticity (가격탄력성을 이용한 전기자동차 충전요금제에 따른 연계계통의 안정성 분석)

  • Kim, Junhyeok;Kim, Joorak;Kim, Chulhwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.9
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    • pp.1577-1582
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    • 2016
  • Now we are facing severe environmental issues such as global warming. Due to these, the concerns about eco-friendly energy have been increased. Kyoto protocol and Copenhagen climate change conference are circumstantial evidence of it. With these trends, the interests for the Electric Vehicles(EVs) which do not emit any harmful gases have gradually been raised. Unfortunately, however, massive connection of EVs to the power system could cause negative impacts such as voltage variations, frequency variations and increase of demand power. To prevent the mentioned issues, KEPCO adopts Time-of-Use(ToU) price for EVs charging. Nevertheless, it is important to verify the propriety of the charging system. In this paper, therefore, we used pre-introduced price elasticity concept to predict possible Demand Response(DR) on charging of EVs. And analyzed possible demand power increase according to various price elasticities. Simulation results show that given ToU based charging system would not enough to control the increase of demand power by EVs on the power system. It is concluded, therefore, additional methods and/or algorithms are required.

Design and Implementation of Charger Monitoring System Based on CAN Protocol (CAN 통신 기반 충전 모니터링 시스템 설계 및 구현)

  • Choo, Yeon-Gyu;Kim, Hyun-Deok
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.3
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    • pp.541-548
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    • 2012
  • On this paper, we proposed a design rule of charger monitoring system which allow us to watch the charging status and verify it for building the electric chargers infrastructure by spread of electric vehicle. Gathering the charging status of battery by proposed system makes us to enhance the charging algorithm, to interface with BMS(Battery Management System) of electric vehicle, to control the charging process with users. Because the technology of rapid charging is dependant upon various factors such as a performance and stability of battery. We proposed the monitoring system of rapid charger based on CAN protocol that can watch a working status of rapid charger including the charging status of battery with real time and can reduce the charging time of battery with optimized status. We also implement it and evaluate its performance.

A Study on Stable Operation of Li-ion Battery Charging/Discharging System (Li-ion 배터리 충/방전 시스템의 안정적 운영에 관한 연구)

  • Yeo, Sung-Dae;Han, Cheol-Kyu;Cho, Tae-Il;Lee, Kyung-Ryang;Kim, Seong-Kweon
    • The Journal of the Korea institute of electronic communication sciences
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    • v.11 no.4
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    • pp.395-402
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    • 2016
  • When the operation of battery is converted at charging and discharging system based on a DC micro grid, the voltage is fluctuated. And excessive voltage fluctuation could cause damage or failure of charging and discharging equipment. Therefore, in this paper, we studied the operating schedule of the charging and discharging system based on the DC micro grid and a design point of the capacitor which was able to reduce the voltage fluctuation. A result of computer simulation showed that when a fluctuation-reducing capacitor which had an initial value of 600V/35mF was applied at the charging and discharging system based on a DC micro grid which was operated with three charging battery sets and five discharging battery sets, voltage fluctuation by charging and discharging operation was reduced by about 63.3%. Furthermore, voltage fluctuation which occurred when initial network voltage was stabilized was reduced by about 73%.