Abstract
An improved irreversible closed modified simple Brayton cycle model with one isothermal heating process is established in this paper by using finite time thermodynamics. The heat reservoirs are variable-temperature ones. The irreversible losses in the compressor, turbine, and heat exchangers are considered. Firstly, the cycle performance is optimized by taking four performance indicators, including the dimensionless power output, thermal efficiency, dimensionless power density, and dimensionless ecological function, as the optimization objectives. The impacts of the irreversible losses on the optimization results are analyzed. The results indicate that four objective functions increase as the compressor and turbine efficiencies increase. The influences of the latter efficiency on the cycle performances are more significant than those of the former efficiency. Then, the NSGA-II algorithm is applied for multi-objective optimization, and three different decision methods are used to select the optimal solution from the Pareto frontier. The results show that the dimensionless power density and dimensionless ecological function compromise dimensionless power output and thermal efficiency. The corresponding deviation index of the Shannon Entropy method is equal to the corresponding deviation index of the maximum ecological function.
Highlights
Refs. [10,11,12], which were the initial work of the Finite time thermodynamics (FTT) theory
The results obtained in this paper will reveal the original results in Refs. [10,11,12], which were the initial work of the FTT theory
When CH1 = CL → ∞, Equations (30)–(34) can be simplified into the performance indicators of the irreversible simple BCY with an isothermal heating process (IHP) and coupled to constant-temperature heat reservoirs (CTHRs) whose T − s diagram is shown in Figure 3a: n
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Considered the variable isothermal pressure drop ratio (πt ), established an improved isothermal heating regenerative BCY model, and studied the regenerator’s role on cycle performance. Tang et al [104] considered the variable πt and established an improved irreversible binary BCY model modified by isothermal heating. In applying the FTT, the heat transfer was introduced into the thermodynamic analysis of the thermodynamic process, and finite temperature difference was considered in. [11,12] will be used, and the finite temperature difference will be considered when establishing the model, which is the key relation among this paper and the Refs. With the W, η, P and E, respectively, as the OPOs, an improved irreversible closed modified simple BCY with one IHP and coupled to variable-temperature heat reservoirs (VTHRs) will be optimized, and the optimization results will be compared. The results obtained in this paper will reveal the original results in Refs. [10,11,12], which were the initial work of the FTT theory
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