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

Abstract

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.

Elevated biogas production from the anaerobic co-digestion of farmhouse waste: Insight into the process performance and kinetics

“…The versatile use of biogas as well as the production of valuable bio-fertiliser will play a key role in the agricultural chain. However, there are ambiguous facets not clearly investigated, namely the case of multiple waste streams, microbiome, or end-products (Baek et al, 2018; Éles et al, 2019; Huang et al, 2017; Koç et al, 2019; Owczuk et al, 2019; Xu et al, 2017).…”

Experiments on Heat Transfer of Supercritical Pressure Kerosene in Mini Tube under Ultra-High Heat Fluxes

“…The validation range was as follows: p = 12 MPa, G = 5000-40,000 kg/m 2 s. q = 1.68-16.8 kW/m 2 and Re = 1.7 × 10 4 -4.6 × 10 5 . The data were validated using the modified Dittus-Boelter correlation Equation (2). As shown in Figure 3, the experimental data fit well with the classic correlation, and the majority of the data were predicted within the error lines of ±15%.…”

“…Supercritical fluids have been extensively studied since the 1960s, because of the urgent demand from a number of new technologies, such as supercritical water-cooled reactors, supercritical CO 2 Brayton cycles, and supercritical organic Rankine cycles [1][2][3]. In particular, thermal management technology is urgently required for advanced aerospace vehicles, including supersonic combustion ramjet (scramjet) and rocket engines.…”

Energy and Exergy Analysis of a Kalina Cycle Used for Combined Heat-Power Systems

“…(MATHEMATICAL METHOD) Kalina sistemini yalnızca termodinamiğin birinci kanunu ile analiz etmek yeterli olmayacaktır. Bu nedenle ikinci kanun analizinin de yapılması gerekmektedir [31][32][33][34][35]. Kalina çevriminin enerji ve ekserji analizi anlık olarak elde edilen veriler göz önünde bulundurularak yapılacaktır.…”