Ecological performance analysis and optimization of energy production systems

ABSTRACTIn recent years, many optimization studies based on various objective functions have beencarried out for different energy production systems by using classical and finite-timethermodynamic theories. In these optimization studies, power output, thermal efficiency,entropy generation rate, power density, exergy, thermoeconomic, exergoeconomic andecological criteria are taken as objective functions. During the last two decades, the analysisof the effects of energy production systems on the environment has gained importance due todrastical decrease on natural sources. For this purpose, authors have studied the ecologicalperformance of different energy production systems. Due to the ecological objective functiongiven in the literature can take negative values, is dimensional and its physical definition isnot clear, a dimensionless and physically more definite and clear significant alternativeecological performance criterion has been defined. This criterion has been named afterEcological Coefficient of Performance (ECOP) and defined as the ratio of power output to theloss rate of availability.In this work, the ecological optimization technique defined in the thesis has been applied todifferent energy production systems (Carnot heat engine, gas turbines, internal combustionheat engines, refrigerators and heat pumps) and optimum performans and design conditionshave been investigated. In this context, the optimal entropy generation rate, thermal efficiencyand power output have been determined for different objective functions and the obtainedresults are compared. Furthermore, the effects of general parameters i.e., the ratio of heatreservoir temperatures, internal irreversibility parameter, heat leak parameter and the effectsspecific parameters relating to each energy production systems on the general and optimumecological performances have been examined and discussed. The defined ecologicalperformance criterion has been proven, the most appropriate performance in terms poweroutput, thermal efficiency and entropy generation rate. In this study, the given performanceanalysis and the obtained optimization results can provide a general theoretical basis foroptimum thermo-ecological design of energy production systems.Key words: Thermo-ecology, finite-time thermodynamics, endoreversible and irreversibleheat engine models, ecologic objective function, maximum ecological performanceconditions, thermal efficiency, entropy generation.xiii