• Journal of the Korean Solar Energy Society
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• v.35 no.5
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• pp.11-19
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• 2015

In this paper, EP-Kalina cycle applying liquid-vapor ejector and motive pump is newly proposed. In this EP-Kalina cycle, the liquid-vapor ejector is used to increase pressure difference between inlet and outlet of the turbine. Also the motive pump enhances the performance of liquid-vapor ejector, resulting in increase of system efficiency of OTEC cycles. The comparison cycles in this study are basic, Kalina, EKalina and EP-Kalina ones. The pump work, net power, APRe, APRc, TPP and system efficiency of each cycle are compared. In case of net power, EP-Kalina cycle is lowest among the cycles due to the application of the motive pump. But, the net power difference of cycles seems to be minor since the pump work of cycles is merely about 1kW, compared to turbine gross power of 20kW. The system efficiency of EP-Kalina cycle shows 3.22%, relatively 44% higher than that of basic OTEC cycle. Therefore, the system efficiency is increased by applying the liquid-vapor ejector and the motive pump. Additional performance analysis is necessary to optimize the proposed EP-Kalina cycle.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.120-125
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• 2014

In this paper, suitable working fluid of 1MW Organic Rankine Cycle(ORC) with liquid-vapor ejector using effluent from power plant is selected. The results of comparison performance of 5 refrigerants are as follows; R600a, R134a, R1270, R236fa, R235fa. The operating parameters considered in this study include the condensation capacity evaporation capacity and efficiency. As a result of comparison of basic ORC system and with liquid-vapor ejector, with ORC system presents the higher system efficiency since the ejector makes the turbine outlet pressure lower than condensation pressure through its pressure recovery. Also, this ejector ORC system is advantageous in miniaturizing the size of components owing to decrease of evaporation capacity and condensation capacity.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.5-13
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• 1999

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.873-880
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• 2010

The present study developed a computer simulation program to determine the optimum strategy and capacity of a micro combined heat and power(CHP) system. This simulation program considered a part-load electrical/thermal efficiency and transient response characteristics of CHP unit. The result obtained from the simulation was compared with the actual operation of 30 kW gas engine driven micro CHP system. It was found that the simulation could reproduce the daily operation behavior, such as operating hours and mean load factor, closely to the actual behavior of the system and could predict the amount of electrical/thermal output and fuel consumption with the error of less than 12%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.397-400
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• 2007

Indoor air-conditioning system(IAS) using wireless sensor network serves to reduce the amount of pollution entering the room from outside and also the pollution that is generated indoor. Small-size and lower power wireless sensor node and sensor interface board was designed for indoor air-conditioning system in buildings of offices and industrial establishments. Many sensor nodes forms Ad-hoc network topology using simple forwarding routing to transmit polluting gas concentration data from different rooms to the indoor air-conditioning system. Sensor node analyzes pollution concentration in the each room and air-conditioning system performs to air-distribution and air-inhalation according to room's pollution by regulating the fan of indoor air-conditioning system. To reduce power consumption electrochemical gas sensor was used in the design. Thus the designed system can optimize state of indoor environment. Graphic user interface displays node sate, gas concentration and temperature of each room.

• Journal of Power Electronics
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• v.9 no.2
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• pp.300-307
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• 2009

In this paper, design and control is proposed for a four input-series-output-series-connected ZVS full bridge converter for the photovoltaic power conditioning system (PCS). The novel topology for a photovoltaic (PV) DC/DC converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing PV module characteristics is proposed. The control scheme, including an input voltage controller is proposed to achieve equal sharing of the input voltage as well output voltages by a four series connected module. Design methods for ZVS power stage are also introduced. The total PV system is implemented for a 250-kW PV power conditioning system (PCS). This system has only three DC/DC converters with a 25-kW power rating and uses only one-third of the total PV PCS power. The 25-kW prototype PV DC/DC converter is introduced to verify experimentally the proposed topology. In addition, an experimental result shows that the proposed topology exhibits good performance.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.140-145
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• 2014

Exploitation of renewable energies is on the increase to mitigate the reliance on fossil fuels and other natural gases with rocketing prices currently due to the depletion of their reserves not to mention their diverse consequences on the environment. Divergently, there are lots of industries "throwing" heat at higher temperatures as by products into the environment. This waste heat can be recovered through organic Rankine systems and converted to electrical energy with a waste heat recovery organic Rankine cycle system (WHR-ORC). This study uses the annual average condenser effluent from Namhae power plant as heat source and surface seawater as cooling source to analyze a waste heat recovery organic Rankine cycle using the Aspen HYSYS simulation software package. Hydrocarbon mixtures are employed as working fluid and varied in a ratio of 9:1. Results indicate that Pentane/Isobutane (90/10) mixture is the favorable working fluid for optimizing the waste heat recovery organic Rankine cycle at the set simulation conditions.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1061-1063
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• 2001

This paper proposes a new power conditioning system for the SMES composed of a thyristor PWM converter with a resonant commutation circuit. The operation of the proposed system and the dynamic interaction between SMES and the power system is analyzed by a theoretical approach with equivalent circuits and verified by computer simulations with EMTP, considering a typical 154kV power system. The proposed system can provide a solution for the power factor regulation and harmonic level reduction in the ac terminal with low-cost system configuration.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.6
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• pp.293-299
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• 2001

This paper proposes a new power conditioning system for the SMES composed of a thyristor PWM converter with a resonant commutation circuit. The operation of the proposed system and the dynamic interaction between SMES and the power system is analyzed by a theoretical approach with equivalent circuits and verified by computer simulations with EMTP, considering a typical 154kV power system. The proposed system can provide a solution for the power factor regulation and harmonic level reduction in the ac terminal with low-cost system configuration.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1728-1734
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• 2009

This paper proposes a new power conditioning system for the fuel cell power generation, which consists of a ZVS DC-DC converter and 3-phase inverter. The ZVS DC-DC converter with a digital controller boosts the fuel cell voltage of 26-50V up to 400V, and the grid-tie inverter controls the active power delivered to the grid. The operation of proposed power conditioning system was verified through simulations with PSCAD/EMTDC software. The feasibility of hardware implementation was verified through experimental works with a laboratory prototype, which was built with 1.2kW PEM fuel-cell stack, 1kW DC-DC converter, and 3kW PWM inverter. The proposed system can be utilized to commercialize an interconnection system for the fuel-cell power generation.