• Title/Summary/Keyword: Entransy dissipation

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Energy and Entransy Characteristic Analysis of Heat Exchangers Depending on Heat Exchanger Type (열교환기 형식에 따른 열교환기의 에너지 및 엔트랜시 성능 특성 해석)

  • KIM, KYOUNG HOON;JUNG, YOUNG GUAN;HAN, CHUL HO
    • Transactions of the Korean hydrogen and new energy society
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    • v.31 no.1
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    • pp.112-121
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    • 2020
  • In this work energy and entransy characteristics of heat exchangers are analyzed for 12 different flow arrangements of heat exchangers. The dimensionless parameters are number of entransy dissipation (Ng), number of entransy dissipation-based thermal resistance (Nr), and entransy dissipation-based effectiveness of heat-exchanger (εg). The dimensionless parameters are expressed analytically in terms of the effectiveness of heat exchanger (ε), heat capacity ratio (c), and number of transfer unit (N) for optimal performance of heat exchangers. Results showed that the dimensionless parameters based on the entransy dissipation can be useful concepts for optimal design of heat exchangers.

Optimal Analysis of Irreversible Carnot Cycle Based on Entransy Dissipation (엔트랜시 소산에 기반한 비가역 카르노 사이클의 최적 해석)

  • Kim, Kyoung Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.41 no.2
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    • pp.87-95
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    • 2017
  • The concept of entransy has been proposed recently as a potential heat transfer mechanism and could be useful in analyzing and optimizing the heat-work conversion systems. This work presents an entransy analysis for the irreversible Carnot cycle by systematic balance formulations of the entransy loss, work entransy, and entransy dissipations, which are consistent with exergy balances. Additionally, several forms of system efficiency are introduced based on entransy for the appreciation of the optimal system performance. The effects of the source temperature and irreversible efficiencies on the optimal conditions for system efficiencies are systematically investigated for both dumping and non-dumping cases of used source fluid. The results show different trends in entransy efficiencies when compared to the conventional efficiencies of energy and exergy, and represent another method to assess the effective use of heat source in power generation systems.

Performance Characteristics Analysis of Evaporator in Ammonia-Water Rankine Cycle Based on Exergy and Entransy (암모니아-물 랭킨사이클의 증발기에서의 엑서지 및 엔트랜시 성능 특성 해석)

  • KIM, KYOUNG HOON;JUNG, YOUNG GUAN
    • Transactions of the Korean hydrogen and new energy society
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    • v.30 no.6
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    • pp.621-628
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    • 2019
  • The use of the ammonia-water zeotropic mixture as a working fluid in the power generating system has been considered as a proven technology for efficient recovery of low-grade heat sources. This paper presents a thermodynamic performance analysis for ammonia-water evaporator using low-grade heat source, based on the exergy and entransy which has been recently introduced as a physical quantity to describe the heat transfer ability of an object. In the analysis, effects of the ammonia mass fraction and source temperature of the binary mixture are investigated on the system performance such as heat transfer, effectiveness, exergy destruction, entransy dissipation, and entransy dissipation based thermal resistance. The results show that the ammonia mass concentration and the source temperature have significant effects on the thermodynamic system performance of the ammonia-water evaporator.