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Effect of heat extraction optimization with supercritical carbon dioxide on transcritical power cycle
Author(s) -
Hsieh JuiChing
Publication year - 2020
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.5344
Subject(s) - supercritical fluid , thermodynamics , transcritical cycle , supercritical carbon dioxide , organic rankine cycle , extraction (chemistry) , heat transfer , materials science , carbon dioxide , chemistry , analytical chemistry (journal) , heat exchanger , chromatography , heat pump , waste heat , physics , organic chemistry
Summary An experimental and thermodynamic analysis was conducted to explore the match in operating conditions for the heat extraction of supercritical CO 2 and the CO 2 transcritical organic Rankine cycle (CTORC). The results revealed that in the optimal conditions of the experiment, the difference between the pseudocritical temperature and the inlet temperature ( ΔT pc − in ) was <10 K and T b /T pc (ratio of the bulk temperature to the pseudocritical temperature) was ≤1 (ideal scenario: T b /T pc = 1). Furthermore, the heat transfer and fluid flow of CO 2 as well as the CTORC system performance at the optimal T b /T pc could be simultaneously improved with respect to those at ΔT pc − in < 10 K. The peak values of system efficiency for the inlet temperature of the expander of 100°C and 150°C were 5.1% at 12.5 MPa and 8.0% at 17 MPa, with the corresponding T b /T pc being 1.24 ( T pc of 55.9°C) and 1.45 ( T pc of 70°C), respectively. Consequently, to simultaneously improve the heat transfer, fluid flow and system efficiency, T pc of the supercritical CO 2 in the CTORC should be sufficiently high to approach half the inlet temperature of the expander for obtaining an optimal T b /T pc at a low condensing temperature.