Thermo-ecological Performance Research Articles

Thermodynamic mapping of A321-200 in terms of performance parameters, sustainability indicators and thermo-ecological performance at various flight phases

In this paper, the performance parameters, sustainability indicators and thermo-ecological parameters are presented to the literature by modelling 140.56 kN propulsion turbofan engine of the A321-200 registered to the International Aero Engines manufacturer under type code 3IA008 and type name V2533-A5. In the study, firstly, exergy efficiency of each component is calculated by two different approaches, and then four different depletion ratios of each component are determined. In addition, the exergetic improvement potential ratios of components and systems are presented. Waste exergy ratio, recoverable exergy rate, exergy destruction factor, environmental effect factor and exergetic sustainability index has been selected as sustainability indicators. Finally, the ECOP (ecological coefficient of performance) function is calculated and comparatively evaluated in the specified flight phases as well as the flight phases are classified in terms of sustainability and environmental impacts. The element emphasizing the originality of this article is that the sustainability and environmental impacts in all flight phases are mapped.

Performance assessment of a modified power generating cycle based on effective ecological power density and performance coefficient

Thermo-ecological performance optimisation and analyses of an engine running with a modified power generating cycle are carried out based on effective ecological power density (EFECPOD) and effective ecological performance coefficient (EFECPEC). They provide a unique value for combined characteristics of thermal efficiency, power, cycle volume, entropy generation and maximum combustion temperature. The impacts of design and operational parameters such as compression ratio, equivalence ratio, engine speed, exhaust temperature ratio, pressure ratio, cycle pressure ratio and cycle temperature ratio on maximum EFECPOD and EFECPEC have been examined for modified power generating cycle.

Performance assessment of a modified power generating cycle based on effective ecological power density and performance coefficient

Thermo-ecological performance optimisation and analyses of an engine running with a modified power generating cycle are carried out based on effective ecological power density (EFECPOD) and effective ecological performance coefficient (EFECPEC). They provide a unique value for combined characteristics of thermal efficiency, power, cycle volume, entropy generation and maximum combustion temperature. The impacts of design and operational parameters such as compression ratio, equivalence ratio, engine speed, exhaust temperature ratio, pressure ratio, cycle pressure ratio and cycle temperature ratio on maximum EFECPOD and EFECPEC have been examined for modified power generating cycle.

Optimization of absorption systems: case of the refrigerators and heat pumps

The new thermo-ecological performance optimization of absorption is investigated by taking the ecological coefficient of performance ECOP as an objective function. ECOP has been expressed in terms of the temperatures of the working fluid in the main components of the system. The maximum of ECOP and the corresponding optimal temperatures of the working fluid and other optimal performance design parameters such as coefficient of performance, specific cooling load of absorption refrigerators, specific heating load of absorption heat pumps, specific entropy generation rate and the distributions of the heat exchanger areas have been derived analytically. The obtained results may provide a general theoretical tool for the ecological design of absorption refrigerators and heat pumps.

Thermo-ecological performance analysis of a double-reheat Rankine cycle steam turbine system (RCSTS) with open and close feed water heaters

This study presents the exergetic and thermo-ecological performance optimisation of a Rankine cycle steam turbine system (RCSTS) consisting of three turbines, one open feed water heater (OFWH) and two closed feed water heaters (CFWHs). In this study, different performance characteristics such as effective power, effective power density, exergy efficiency, exergy destruction and ecological coefficient of performance (ECOP) are used to investigate and optimise the system performance. The effects of condenser pressure, OFWH pressure and reheat pressures on the performance characteristics of the system have been examined by considering the irreversibilities and system properties. The results showed that the component pressures considerably affect the system performance. Therefore, they should be optimised to obtain maximum performance characteristics.

Thermo-ecological performance analysis of a double-reheat Rankine cycle steam turbine system (RCSTS) with open and close feed water heaters

Thermo-ecological performance analysis of a double-reheat Rankine cycle steam turbine system (RCSTS) with open and close feed water heaters

Exergetic and Thermo-ecological performance analysis of a Gas-Mercury combined turbine system (GMCTS)

This study presents the exergy and thermo-ecological performance optimization of a Gas-Mercury combined turbine system (GMCTS). Power output, power density, exergetic efficiency, total exergy destruction, ecological coefficient of performance (ECOP) and effective ecological power density (EFECPOD) are examined for the combined system. The influences of gas turbine speed, pressure ratio, air mass rate, equivalence ratio, air intake temperature and pressure of the gas turbine, residual gas fraction, mercury temperature of heat exchanger, temperature of the extracted mercury from mercury low pressure turbine (MLPT), mercury outlet temperature of the mercury medium pressure turbine (MMPT), mercury outlet temperature of the mercury high pressure turbine (MHPT) on the performance characteristics of the combined system have been examined by taking the irreversibilities and system properties into account. The results demonstrated that the component pressures and temperatures considerably affect the performance characteristics of the GMCTS. This study is novel and unique in terms of understanding of the effects of the system design and operating parameters altogether on the exergetic and thermo-ecological performance of the GMCTS.

A comparative thermo-ecological performance analysis of generalized irreversible solar-driven heat engines

In this study, an analysis based upon thermo-ecology criteria has been performed for an irreversible solar-driven heat engine. In the conceived heat engine, heat is transferred by using simultaneous radiation and convection mode from the source at high temperature to the heat engine side and by using convection mode from the heat engine to the source at low temperature. The influences of the optimization variables on the thermo-ecologic performance have been observed by using the ecologic objective function and the ecological coefficient of performance (ECOP). Also various performance factors of the heat engine, such as thermal efficiency, power output, loss rate of availability and temperatures of the working fluid have been discussed in detail by considering the maximum ecological coefficient of performance, maximum ecological function and maximum power output conditions. The entropy generation rate at maximum ECOP is less than at maximum ecologic objective function conditions, while the power output at maximum ECOP is less than at maximum ecologic objective function conditions.

Thermo-ecological performance analysis of a Joule-Brayton cycle (JBC) turbine with considerations of heat transfer losses and temperature-dependent specific heats

This study presents a new performance analysis criterion called Effective Ecological Power Density (EFECPOD) and its application to a Joule-Brayton cycle (JBC) turbine. Effective efficiency (EE), effective power (EP), cycle temperature ratio and turbine volume are considered together and the performance is stated a unique value by the developed criterion. emissions formation and turbine dimensions are considered by the cycle temperature ratio and turbine volume, respectively. The turbine volume is also related to production cost of the heat engine. Therefore, the proposed criterion is essential for multipurpose optimization. Furthermore, this criterion can be developed and applied to the other gas cycles and heat engines. Also, a performance investigation for the JBC gas turbine in terms of EE, EP and effective power density (EPD) has been carried out using a new finite-time thermodynamics modeling (FTTM). The influences of engine design parameters such as cycle temperature ratio, cycle pressure ratio, turbine speed, intake temperature, intake pressure and equivalence ratio on the EE, EP, EPD and EFECPOD have been examined. The results presented can be an essential tool for JBC turbine designers.

Thermo-ecological performance analyses and optimizations of irreversible gas cycle engines

This paper reports ecological performance analyses and optimization of irreversible gas cycle engines such as Joule–Brayton cycle (JB), Atkinson cycle (AC), Otto cycle (OC), Diesel cycle (DC), Miller cycle (MC), Dual-Atkinson cycle (DAC), Dual-Diesel cycle (DDC), Dual-Miller cycle (DMC) engines based on the ecological coefficient of performance (ECOP) criterion which covers internal irreversibility, heat leak and finite-rate of heat transfer. Comprehensive computational analyses have been conducted to investigate the global and optimal performances of the gas cycle engines. The results obtained based on the ECOP criterion are compared with a different ecological function which is named as the ecologic objective-function and with the maximum power output conditions. The results have been acquired introducing the compression ratio, cut-off ratio, pressure ratio, air recharging ratio, source temperature ratio and internal irreversibility parameter. The changes of cycle performances with respect to these parameters are examined and demonstrated with figures.

Optimal performance of an absorption refrigerator based on maximum ECOP

A general cycle model including several major irreversibilities existing usually in real absorption refrigeration systems is established and used to investigate the new thermo-ecological optimal performance of a four-heat-source refrigerator affected by the irreversibilities of finite-rate heat transfer between the working fluid and the external heat reservoirs, heat leak losses of the cooled space, and internal dissipation of the working fluid. The ecological coefficient of performance (ECOP) of the cycle system is used as objective functions for optimization. The ECOP objective function is defined as the ratio of the cooling load to the loss rate of availability (or entropy generation rate). The maximum of the new thermo-ecological performance criterion and the corresponding optimal conditions have been derived analytically. The effects of irreversibility parameters on the general and optimal performances are discussed detailed. The practical operating region of the four-heat-source refrigerator is discussed. The obtained results may provide a general theoretical tool for the ecological design of four-heat-source absorption refrigerators.

Optimal ecological performance of a four-temperature-level absorption heat pump

The new thermo-ecological performance optimization that combines first and second law of thermodynamics has been carried out for an irreversible absorption heat pump operating between four-temperature-levels. Multi-irreversibilities considered in the system include finite-rate transfer, heat leakage and internal dissipations. The ecological coefficient of performance ECOP defined as the ratio of the heating load to the loss rate of availability (or entropy generation rate) is considered as the objective function. The goal of the new thermo-ecological performance optimization is to maximize this objection function with respect to the working fluid temperatures in the main components of the system. The maximum ECOP and the corresponding optimal coefficient of performance, specific heating load, specific entropy production rate and heat-transfer areas have been determined analytically. The effects of the internal irreversibility, the heat leakage coefficient, the source temperature ratios, the overall heat-transfer coefficients of the heat-exchangers and the distribution ratio rate of the total heat-reject quantity between the absorber and the condenser on the global and optimal performances have been analyzed and discussed.

The new thermo-ecological performance optimization of an irreversible three-heat-source absorption heat pump

The new thermo-ecological performance optimization of an absorption heat pump operating between three temperature levels with the losses of heat resistance, internal irreversibility and leakage is analyzed by taking the ecological coefficient of performance (ECOP) as an objective function. The new thermo-ecological criterion takes into account the first and second law of thermodynamics and is defined as the heating rate per unit loss rate of availability. The ecological coefficient of performance has been expressed and maximized in terms of the temperatures of the working fluid in the main components of the system. The corresponding optimal temperatures and other optimum performance parameters have been derived analytically, and the effects of the internal irreversibility, the heat leakage coefficient and the source temperature ratio on the global and optimal performances are discussed. The obtained results may provide a general theoretical tool for the ecological design of absorption heat pumps.

Effect of regeneration on the thermo-ecological performance analysis and optimization of irreversible air refrigerators

A thermo-ecological performance analysis of an irreversible regenerative air refrigerator cycle exchanging heat with thermal reservoirs is presented. In the analysis, the external irreversibility effects due to heat transfer across finite temperature differences and the heat leak loss between the external heat reservoirs while the internal irreversibilities are due to the non-isentropic compression and expansion processes and the regenerative loss are taken into account. The effects of regeneration and heat sources temperature ratio are given special emphasis and investigated in detail. A comparative performance analysis considering the objective functions of an ecological coefficient of performance, exergetic efficiency and coefficient of performance is also carried out. The maximum of the objective functions and the corresponding optimal conditions have been derived analytically. The obtained results may provide a general theoretical tool for the thermo-ecological design of regenerative air refrigerators.

Thermo-ecological performance optimisation of two stage irreversible refrigerators

The present study investigates the optimal performance of two stage refrigeration system based on thermo-ecological performance criterion. To maximise the ecological performance function, the working fluid temperatures are optimised. The optimal conditions such as cooling load, entropy generation rate and Coefficient of Performance (COP) are arrived analytically. The derived solution provides a general theoretical tool for ecological design of the two stage refrigerators. In this analysis, the effects of irreversibilities such as finite rate of heat transfer and heat leakage on the ecological performance are considered. The study also investigates the effect of intermediate temperature ratio and source temperature ratio on the ecological performance function.

The effects of intercooling and regeneration on the thermo-ecological performance analysis of an irreversible-closed Brayton heat engine with variable-temperature thermal reservoirs

A thermo-ecological performance analysis of an irreversible intercooled and regenerated closed Brayton heat engine exchanging heat with variable-temperature thermal reservoirs is presented. The effects of intercooling and regeneration are given special emphasis and investigated in detail. A comparative performance analysis considering the objective functions of an ecological coefficient of performance, an ecological function proposed by Angulo-Brown and power output is also carried out. The results indicate that the optimal total isentropic temperature ratio and intercooling isentropic temperature ratio at the maximum ecological coefficient of performance conditions (ECOPmax) are always less than those of at the maximum ecological function () and the maximum power output conditions () leading to a design that requires less investment cost. It is also concluded that a design at ECOPmax conditions has the advantage of higher thermal efficiency and a lesser entropy generation rate, but at the cost of a slight power loss.