Thermodynamic optimisation of a high-electrical efficiency integrated internal combustion engine – Organic Rankine cycle combined heat and power system

Chatzopoulou, Maria Anna; Markides, Christos N.

doi:10.1016/j.apenergy.2018.06.022

Cited by 67 publications

(31 citation statements)

References 64 publications

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“…Chatzopoulou and Markides thermodynamically optimized an ORC-assisted internal combustion engine using R245fa. As a result of the optimization, thermal and exergy efficiencies of the ORC was calculated as 14% and 33%, respectively [62]. In the present study, at the same turbine inlet temperature and pressure, the net power production per mass flow rate, thermal and exergy efficiencies were calculated as 36.25 kJ/kg, 15.78% and 27.17%.…”

Section: Subcritical Rorcmentioning

confidence: 67%

Exergy Analysis and Performance Improvement of a Subcritical/Supercritical Organic Rankine Cycle (ORC) for Exhaust Gas Waste Heat Recovery in a Biogas Fuelled Combined Heat and Power (CHP) Engine Through the Use of Regeneration

2019

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In the present study, a subcritical and supercritical regenerative organic Rankine cycle (rORC) was designed. The designed rORCs assist a combined heat and power (CHP) engine, the fuel of which is biogas produced from anaerobic digestion of domestic wastes in Belgium. R245fa was selected as the working fluid for both the subcritical and supercritical rORC. During the parametric optimisation, the net power production, mass flow rate, exchanged heat in the regenerator, total pump power consumption, thermal and exergetic efficiencies of rORC were calculated for varying turbine inlet temperatures and pressures. After parametric optimisation of the rORC, the results were compared with the results of the previous study, in which only a simple ORC is analysed and parametrically optimised. Moreover, the effect of the regenerator was revealed by examining all results together. Finally, the exergetic analysis of the best performing subcritical and supercritical rORC was performed. Furthermore, the results of the present and previous studies were considered together and it is clearly seen that the subcritical rORC shows the best performance. Consequently, by using the subcritical rORC, the disadvantages of the using simple ORC (low performance) and supercritical cycle (safety, investment) can be eliminated and system performance can be improved.

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Section: Subcritical Rorcmentioning

confidence: 67%

Exergy Analysis and Performance Improvement of a Subcritical/Supercritical Organic Rankine Cycle (ORC) for Exhaust Gas Waste Heat Recovery in a Biogas Fuelled Combined Heat and Power (CHP) Engine Through the Use of Regeneration

2019

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“…where m denotes a mass flow rate; h a specific enthalpy; T and P are temperatures and pressures, respectively; Qe and Qc are the heat duty of the evaporator and the condenser, respectively; Wp, We and Wnet are the pump power consumption, the expansion power output and the net power output from the system, respectively; ηp and ηe are the (fixed [15,17]) isentropic efficiencies of the pump and the expander; cp is a specific heat capacity. Furthermore, subscripts '1'-'6' denote thermodynamic states; 'f', 'g' and 'cw' refer to the working fluid, exhaust gas and cooling water, respectively; 'in' and 'out' to the inlet and outlet; and 's' signifies an isentropic process.…”

Section: Orc Thermodynamic Modelmentioning

confidence: 99%

“…Investigations on ORC technology for converting recovered waste-heat from ICEs have been conducted both computationally and experimentally [9,10], including on configuration design [11][12][13] and system optimization [14][15][16], working fluid selection by traditional pre-selection (including pure fluids [17,18] and mixtures [19,20]) and by new computer-aided molecular design methods [21][22][23] integrated into cycle optimization [24,25], expander selection and design [26,27] (including piston [28][29][30], screw [31][32][33] and rotary-vane [34] expanders), and off-design performance [35,36]. These excellent studies have enabled significant progress with the performance of ORC technology towards through careful considerations of the working fluid, key components and system parameters.…”

Section: Introductionmentioning

confidence: 99%

Organic Rankine cycle systems for engine waste-heat recovery: Heat exchanger design in space-constrained applications

Song

et al. 2019

Energy Conversion and Management

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Organic Rankine cycle (ORC) systems are a promising solution for improving internal combustion engine efficiencies, however, conflicts between the pressure drops in the heat exchangers, overall thermodynamic performance and economic viability are acute in this space-constrained application. This paper focuses on the interaction of the heat exchanger pressure drop (HEPD) and the thermo-economic performance of ORC systems in engine waste-heat recovery applications. An iterative procedure is included in the thermo-economic analysis of such systems that quantifies the HEPD in each case, and uses this information to revise the cycle and to resize the components until convergence. The newly proposed approach is compared with conventional methods in which the heat exchangers are sized after thermodynamic cycle modelling and the pressure drops through them are ignored, in order to understand and quantify the effects of the HEPD on ORC system design and working fluid selection. Results demonstrate that neglecting the HEPD leads to significant overestimations of both the thermodynamic and the economic performance of ORC systems, which for some indicators can be as high as >80% in some cases, and that this can be effectively avoided with the improved approach that accounts for the HEPD. In such space-limited applications, the heat exchangers can be designed with a smaller cross-section in order to achieve a better compromise between packaging volume, heat transfer and ORC net power output. Furthermore, we identify differences in working fluid selection that arise from the fact that different working fluids give rise to different levels of HEPD. The optimized thermo-economic approach proposed here improves the accuracy and reliability of conventional early-stage engineering design and assessments, which can be extended to other similar thermal systems (i.e., CO2 cycle, Brayton cycle, etc.) that involve heat exchangers integration in similar applications.

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“…Baidya et al [37] described the implementation of ORC for waste heat recovery of Diesel generators in off-the-grid locations. Chatzopoulou et al [38] performed a whole system optimization of an integrated Diesel generator and ORC for combined heat and power, and then investigated the off-design conditions with varying conditions of the engine [39].…”

Section: Orc For Ic Engine Whrmentioning

confidence: 99%

“…ORC direct evaporation from exhaust gases is certainly conceptually much simpler. Therefore, it is very often considered as the option in the literature studies at system level [38], [58], [115] and component level [116].…”

Section: Direct Vs Indirect Evaporationmentioning

confidence: 99%

Designing the dynamic response of Organic Rankine Cycle evaporators in waste heat recovery applications

Jiménez-Arreola¹

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Thermodynamic optimisation of a high-electrical efficiency integrated internal combustion engine – Organic Rankine cycle combined heat and power system

Cited by 67 publications

References 64 publications

Exergy Analysis and Performance Improvement of a Subcritical/Supercritical Organic Rankine Cycle (ORC) for Exhaust Gas Waste Heat Recovery in a Biogas Fuelled Combined Heat and Power (CHP) Engine Through the Use of Regeneration

Exergy Analysis and Performance Improvement of a Subcritical/Supercritical Organic Rankine Cycle (ORC) for Exhaust Gas Waste Heat Recovery in a Biogas Fuelled Combined Heat and Power (CHP) Engine Through the Use of Regeneration

Organic Rankine cycle systems for engine waste-heat recovery: Heat exchanger design in space-constrained applications

Designing the dynamic response of Organic Rankine Cycle evaporators in waste heat recovery applications

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