Abstract
Optimal configurations for the working fluid expansion process in a piston-type cylinder with maximum work production are studied by applying finite time thermodynamics. The problem is solved by utilizing the modified Lagrangian. The initial and final volumes, initial internal energy and total time are fixed, and the heat transfer between the working fluid and the external heat bath obeys the generalized convective heat transfer law, which can be transformed into Newton’s heat transfer law, the Dulong–Petit heat transfer law and the square convective heat transfer law. The optimal configurations of the expansion process under three different conditions of heat transfer law are provided and compared, respectively. The results show that the heat transfer law has both quantitative and qualitative influences on the optimal configurations of the expansion process.
Highlights
IntroductionFinite time thermodynamics (FTT) [1,2,3,4,5,6,7,8,9,10,11,12,13] has been applied to perform performance analyses and optimizations for various thermodynamic cycles and processes, including multi-stream heat exchange system [14], chemical reactors [15,16,17,18], electrochemical device [19], biological process [20], Novikov engines [21,22,23], Agrawal engine [24], Carnot engines [25,26], solar engine [27], internal combustion engine cycles [28,29,30,31,32], thermoelectric devices [33,34,35,36], cogeneration plants [37,38,39], ocean thermal energy conversion plants [40,41,42], Kalina cycle [43], Rankine cycles [44,45,46], Brayton cycles [47,48,49], Maisotsenko cycles [50,51], ratchet engine [52], electron engine [53] and the quantum engine [54]
Bi et al [67] optimized the charging and discharging processes of the gas-hydrate with Newton’s heat transfer law (NHTL) based on the minimum entropy generation criterion, and determined the optimal configurations (OCs) of the temperature and gas-hydrate phase change rate
Some studies on the OCs of the heat engines (HEs) with GRHTL [81], generalized convective HTL (GCHTL) [82] and complex generalized heat transfer laws (HTLs) [83] under condition of variable-temperature heat reservoirs were conducted based on maximum work output (MWP) criterion
Summary
Finite time thermodynamics (FTT) [1,2,3,4,5,6,7,8,9,10,11,12,13] has been applied to perform performance analyses and optimizations for various thermodynamic cycles and processes, including multi-stream heat exchange system [14], chemical reactors [15,16,17,18], electrochemical device [19], biological process [20], Novikov engines [21,22,23], Agrawal engine [24], Carnot engines [25,26], solar engine [27], internal combustion engine cycles [28,29,30,31,32], thermoelectric devices [33,34,35,36], cogeneration plants [37,38,39], ocean thermal energy conversion plants [40,41,42], Kalina cycle [43], Rankine cycles [44,45,46], Brayton cycles [47,48,49], Maisotsenko cycles [50,51], ratchet engine [52], electron engine [53] and the quantum engine [54]. Teh et al [65,66] researched the optimal cycle of adiabatic internal combustion engine (ICE) under the condition of maximum efficiency by considering the heat leakage and chemical reaction loss as major losses of ICEs. Bi et al [67] optimized the charging and discharging processes of the gas-hydrate with NHTL based on the minimum entropy generation criterion, and determined the OCs of the temperature and gas-hydrate phase change rate. Some studies on the OCs of the HEs with GRHTL [81], GCHTL [82] and complex generalized HTL [83] under condition of variable-temperature heat reservoirs were conducted based on MWP criterion.
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