Entropy and Entransy Dissipation Analysis of a Basic Organic Rankine Cycles (ORCs) to Recover Low-Grade Waste Heat Using Mixture Working Fluids

Autor:	Shuang Wang, Qing-song An, Zhixia He, Wang Xin, Yongqiang Feng, Qian Wang, Luo Qianhao, Wei Zhang
Rok vydání:	2018
Předmět:	Materials science 020209 energy General Physics and Astronomy Thermodynamics lcsh:Astrophysics mixture working fluids 02 engineering and technology Heat sink Article chemistry.chemical_compound Entropy (classical thermodynamics) Waste heat lcsh:QB460-466 0202 electrical engineering electronic engineering information engineering lcsh:Science Degree Rankine Organic Rankine cycle Pinch point lcsh:QC1-999 Pentane chemistry organic Rankine cycles (ORCs) lcsh:Q entropy entransy dissipation Mass fraction lcsh:Physics
Zdroj:	Entropy Volume 20 Issue 11 Entropy, Vol 20, Iss 11, p 818 (2018)
ISSN:	1099-4300
DOI:	10.3390/e20110818
Popis:	Mixture working fluids can reduce effectively energy loss at heat sources and heat sinks, and therefore enhance the organic Rankine cycle (ORC) performance. The entropy and entransy dissipation analyses of a basic ORC system to recover low-grade waste heat using three mixture working fluids (R245fa/R227ea, R245fa/R152a and R245fa/pentane) have been investigated in this study. The basic ORC includes four components: an expander, a condenser, a pump and an evaporator. The heat source temperature is 120 ° C while the condenser temperature is 20 ° C. The effects of four operating parameters (evaporator outlet temperature, condenser temperature, pinch point temperature difference, degree of superheat), as well as the mass fraction, on entransy dissipation and entropy generation were examined. Results demonstrated that the entransy dissipation is insensitive to the mass fraction of R245fa. The entropy generation distributions at the evaporator for R245/pentane, R245fa/R152a and R245fa/R227ea are in ranges of 66&ndash 74%, 68&ndash 80% and 66&ndash 75%, respectively, with the corresponding entropy generation at the condenser ranges of 13&ndash 21%, 4&ndash 17% and 11&ndash 21%, respectively, while those at the expander for R245/pentane, R245fa/R152a and R245fa/R227ea are approaching 13%, 15% and 14%, respectively. The optimal mass fraction of R245fa for the minimum entropy generation is 0.6 using R245fa/R152a.
Databáze:	OpenAIRE
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