Abstract
Using finite-time thermodynamics, a model of an endoreversible Carnot cycle for a space power plant is established in this paper. The expressions of the cycle power output and thermal efficiency are derived. Using numerical calculations and taking the cycle power output as the optimization objective, the surface area distributions of three heat exchangers are optimized, and the maximum power output is obtained when the total heat transfer area of the three heat exchangers of the whole plant is fixed. Furthermore, the double-maximum power output is obtained by optimizing the temperature of a low-temperature heat sink. Finally, the influences of fixed plant parameters on the maximum power output performance are analyzed. The results show that there is an optimal temperature of the low-temperature heat sink and a couple of optimal area distributions that allow one to obtain the double-maximum power output. The results obtained have some guidelines for the design and optimization of actual space power plants.
Highlights
Carnot [1] found that the maximum thermal efficiency (TEF) of all thermodynamic cycles under ideal conditions is the Carnot efficiency, which provides the upper limit of TEF for heat engines working between the temperatures of hot- and cold-side heat reservoirs.In order to approach the actual process and reform and improve classical thermodynamics, some scholars [2,3,4] established the endoreversible Carnot heat engine (ECHE) model with only thermal resistance loss considered
Lior [43] analyzed the effects of the main operating parameters of the closed Brayton cycle (CBC) for space power plants on the relationships among the power output (POW) and TEF and the radiator panel area ratio under different working fluid (WF) space conditions
Using finite-time thermodynamics (FTT) theory, a model of an endoreversible Carnot cycle for space plants is established in this paper
Summary
Carnot [1] found that the maximum thermal efficiency (TEF) of all thermodynamic cycles under ideal conditions is the Carnot efficiency, which provides the upper limit of TEF for heat engines working between the temperatures of hot- and cold-side heat reservoirs. Many scholars have optimized the mass and size of the HEX as well as the performance of the entire space power plant. Lior [43] analyzed the effects of the main operating parameters of the CBC for space power plants on the relationships among the POW and TEF and the radiator panel area ratio under different working fluid (WF) space conditions. Some scholars have studied space power plants with FTT theory [45,46,47,48,49]. There are optimal temperatures of the LTHS and a couple of optimum area distributions, which lead to the double-maximum POW Such temperature and area distribution conditions ensure the future design of a plant conversion system that aligns better performances and compactness. The influences of fixed plant parameters on the maximum POW performance are analyzed
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