• Title/Summary/Keyword: Combined heat source

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Comparison of Heat Pump Performance and Energy Consumption Patterns according to Heat Sources for Optimal Control of Multi-Source Heat Pumps (복합열원 히트펌프 최적 제어를 위한 열원에 따른 히트펌프 성능 및 에너지 소요량 패턴 비교)

  • Ko, Yujin;Park, Sihun;Min, Joonki
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.16 no.4
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    • pp.31-38
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    • 2020
  • The investment in the technology of using a combined heat source is insufficient, which utilizes the advantages of various heat sources to maximize the potential energy and at the same time increases the performance of the heat pump. In this study, as basic data for the development of a high-efficiency hybrid heat pump system that actively connects and uses various heat sources, simulations were conducted for the heat pumps in two cases where geothermal and hydrothermal heat were applied respectively. In May, COP increased by about 27.3% compared to geothermal heat. In February, the COP percentage decrease of hydrothermal heat compared to geothermal heat is -6.9%. In May, total energy consumption can be reduced by 21.1% when hydrothermal is applied compared to geothermal heat. In February, the total energy consumption increases by 3.4%.

Analysis of the experimental cooling performance of a high-power light-emitting diode package with a modified crevice-type vapor chamber heat pipe

  • Kim, Jong-Soo;Bae, Jae-Young;Kim, Eun-Pil
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.8
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    • pp.801-806
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    • 2015
  • The experimental analysis of a crevice-type vapor chamber heat pipe (CVCHP) is investigated. The heat source of the CVCHP is a high-power light-emitting diode (LED). The CVCHP, which exhibits a bubble pumping effect, is used for heat dissipation in a high-heat-flux system. The working fluid is R-141b, and its charging ratio was set at 60 vol.% of the vapor chamber in a heat pipe. The total thermal conductivity of the falling-liquid-film-type model, which was a modified model, was 24% larger than that of the conventional model in the LED package. Flow visualization results indicated that bubbles grew larger as they combined. These combined bubbles pushed the working fluid to the top, partially wetting the heat-transfer area. The thermal resistance between the vapor chamber and tube in the modified design decreased by approximately 32%. The overall results demonstrated the better heat dissipation upon cooling of the high-power LED package.

Thermodynamic Performance Characteristics of Organic Rankine Cycle (ORC) using LNG Cold Energy (LNG 냉열을 이용하는 유기랭킨사이클(ORC)의 열역학적 성능 특성)

  • Kim, Kyoung Hoon;Ha, Jong Man;Kim, Kyung Chun
    • Journal of the Korean Institute of Gas
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    • v.18 no.2
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    • pp.41-47
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    • 2014
  • In this work a thermodynamic performance analysis is carried out for a combined cycle consisted of an organic Rankine cycle (ORC) and a LNG cycle. The combined system uses a low grade waste heat in the form of sensible energy and the LNG cold energy is used for power generation as well as for heat sink. The effects of the key parameters of th system such as turbine inlet pressure, condensation temperature and source temperature on the characteristics of system are throughly investigated. The simulation results show that the thermodynamic performance of the combined system can be significantly improved compared to the normal ORC which is not using the LNG cold energy.

A proposal on SOFC-PEMFC combined system for maritime applications

  • Duong Phan Anh;Ryu Borim;Nguyen Quoc Huy;Lee Jinuk;Kang Hokeun
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2022.11a
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    • pp.162-163
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    • 2022
  • Maritime transportation is going to transfer to alternative fuels as a result of the worldwide demands toward decarbonization and tougher maritime emissions regulations. Methanol is considered as a potential marine fuel, which has the ability to reduce SOx and CO2 emissions, reduce climate change effects, and achieve the objective of green shipping. This work proposes and combines the innovative combination system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbines (GT), and organic Rankine cycles (ORC) for maritime vessels. The system's primary power source is the SOFC, while the GT and PEMFC use the waste heat from the SOFC to generate useful power and improve the system's ability to use waste heat. Each component's thermodynamics model and the combined system's model are established and examined. The multigeneration system's energy and exergy efficiency are 76.2% and 30.3%, respectively. When compared to a SOFC stand-alone system, the energy efficiency of the GT and PEMFC system is increased by 19.2%. The use of PEMFC linked SOFC has significant efficiency when a ship is being started or maneuvered and a quick response from the power and propulsion plant is required.

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Development of kW Class SOFC Systems for Combined Heat and Power Units at KEPRI

  • Lee, Tae-Hee;Choi, Jin-Hyeok;Park, Tae-Sung;Yoo, Keun-Bae;Yoo, Young-Sung
    • Journal of the Korean Ceramic Society
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    • v.45 no.12
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    • pp.772-776
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    • 2008
  • The Korea Electric Power Research Institute (KEPRI) has been developing planar solid oxide fuel cells (SOFCs) and power systems for combined heat and power (CHP) units. The R&D work includes solid oxide fuel cell (SOFC) materials investigation, design and fabrication of single cells and stacks, and kW class SOFC CHP system development. Anode supported cells composed of Ni-YSZ/FL/YSZ/LSCF were enlarged up to $15{\times}15\;cm^2$ and stacks were manufactured using $10{\times}10\;cm^2$ cells and metallic interconnects such as ferritic stainless steel. The first-generation system had a 37-cell stack and an autothermal reformer for use with city gas. The system showed maximum stack power of about $1.3\;kW_{e,DC}$ and was able to recover heat of $0.57{\sim}1.2\;kW_{th}$ depending on loaded current by making hot water. The second-generation system was composed of an improved 48-cell stack and a prereformer (or steam reformer). The thermal management subsystem design including heat exchangers and insulators was also improved. The second-generation system was successfully operated without any external heat source. Under self-sustainable operation conditions, the stack power was about $1.3\;kW_{e,DC}$ with hydrogen and $1.2\;kW_{e,DC}$ with city. The system also recuperated heat of about $1.1\;kW_{th}$ by making hot water. Recently KEPRI manufactured a 2kW class SOFC stack and a system by scaling up the second-generation 1kW system and will develop a 5kW class CHP system by 2010.

A Performance Estimation of Ground Source Heat Pump System Used both for Heating and Snow-melting (난방.융설 겸용 지열원 히트펌프시스템의 운전성능 평가)

  • Choi, Deok-In;Kim, Joong-Hun;Hwang, Kwang-Il
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.8 no.1
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    • pp.7-12
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    • 2012
  • This study proposes a hybrid geothermal system combined with heating mode and snow-melting mode for winter season in order to increase the annual operating efficiency of the GSHP(Ground Source Heat Pump). The purpose of this study is to get effectiveness of the hybrid geothermal system by the site experiments. In case of snow-melting only mode, the GSHP COP is 0.7 higher than system COP in average. And in case of hybrid mode, heating GSHP COP is 0.5 higher than snow-melting GSHP COP. And it is also found out that all COP obtained through measurement periods is higher than nominal COPs given by GSHP manufacturer. As a conclusion, it is clear that the proposed hybrid geothermal system is expected as a highly efficient system.

OPTIMAL DESIGN FOR COOLING SYSTEM OF DRIVING UNITS FOR HYBRID VEHICLES (하이브리드 자동차 구동시스템용 냉각 유로 최적화에 관한 연구)

  • Lee, K.H.;Kim, Jae-Won;Ahn, E.Y.
    • Journal of computational fluids engineering
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    • v.14 no.1
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    • pp.62-69
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    • 2009
  • The cooling system for electric devices of hybrid vehicles is examined. The present system is composed of coolant paths, inlet diffuser and heat sinks whose shapes are diamond and circular. In this work, inlet duct and fin arrays are combined in proposed models and examined by numerical calculations. Nusselt number and Reynolds number are considered for heat transfer performance. Main focus lies on the looking for optimal model for the cooling system adopted to compact driving module of a hybrid vehicle. The optimal model shows uniform flow patterns in the inlet diffuser and secondary flows after the fins attached to heat source. It is found that the vortical flows around the heat sinks are effective for heat removal mechanism.

Thermodynamic Performance Analysis of a Cogeneration System in Series Circuit Using Regenerative ORC (재생 유기랭킨사이클을 이용한 직렬 열병합 발전 시스템의 열역학적 성능 특성)

  • KIM, KYOUNG HOON;PARK, BAE DUCK;KIM, MAN-HOE
    • Journal of Hydrogen and New Energy
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    • v.26 no.3
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    • pp.278-286
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    • 2015
  • This paper presents the analytical results of the thermodynamic performance characteristics for a cogeneration system using regenerative organic Rankine cycle (ORC) driven by low-grade heat source. The combined heat and power cogeneration system consists of a regenerative superheated ORC and an additional process heater in a series circuit. Eight working fluids of R134a, R152a, propane, isobutane, butane, R245fa, R123, and isopentane are considered for the analysis. Special attention is paid to the effect of turbine inlet pressure on the system performance such as thermal input, net power and useful heat productions, electrical, thermal, and system efficiencies. The results show a significant effect of the turbine inlet pressure and selection of working fluid on the thermodynamic performance of the system.

Numerical Analysis of Turbulent Combustion and Emissions in an HRSG System (가스터빈 열 회수 증기 발생기의 난류연소 해석과 배기가스 예측 및 검증)

  • Jang, Jihoon;Han, Karam;Park, Hoyoung;Lee, Wook-Ryun;Huh, Kangyul
    • KEPCO Journal on Electric Power and Energy
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    • v.5 no.2
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    • pp.103-111
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    • 2019
  • The combined cycle plant is an integration of gas turbine and steam turbine, combining the advantages of both cycles. It recovers the heat energy from gas turbine exhaust to use it to generate steam. The heat recovery steam generator plays a crucial role in combined cycle plants, providing the link between the gas turbine and the steam turbine. Simulation of the performance of the HRSG is required to study its effect on the entire cycle and system. Computational fluid dynamics has potential to become a useful to validate the performance of the HRSG. In this study a solver has been implemented in the open source code, OpenFOAM, for combustion simulation in the heat recovery steam generator. The solver is based on the steady laminar flamelet model to simulate detailed chemical reaction mechanism. Thereafter, the solver is used for simulation of HRSG system. Three cases with varying fuel injections and gas turbine exhaust gas flow rates were simulated and the results were compared with measurements at the system outlet. Predicted temperature and emissions and those from measurements showed the same trend and in quantitative agreement.

A Study on the GSHP System for Domestic application(I) (GSHP 시스템의 국내적용성에 관한 연구(I))

  • 백성권;안형준;박영진
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.03a
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    • pp.439-444
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    • 2002
  • Geothermal or ground source heat pumps(GSHPs) are electrically powered systems that take advantage of the earth's relatively constant temperature to provide heating, cooling, and hot water for homes and commercial buildings. The buried pipe, or ground loop, is the most recent technical advance in heat pump technology. The idea to bury pipe in the ground to gather heat energy began in the 1940s. Only recently, however, have new heat pump designs and improved buried pipe materials been combined to make GHP systems the most efficient heating and cooling systems available. The aim of the study is application of the GSHP system in korea. Our environments for economy, politics and society are different from other countries. For a case, the progressive tax rate of home electricity is represented.

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