Experimental Investigation and RSM Modeling of the Effects of Injection Timing on the Performance and NO x Emissions of a Micro-Cogeneration Unit Fueled with Biodiesel Blends

Carlo Caligiuri, Marco Bietresato, Angelo Algieri, Marco Baratieri and Massimiliano Renzi
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Carlo Caligiuri: Faculty of Science and Technologies, Free University of Bozen-Bolzano, 39100 Bolzano, Italy
Marco Bietresato: Faculty of Science and Technologies, Free University of Bozen-Bolzano, 39100 Bolzano, Italy
Angelo Algieri: Department of Mechanical, Energy and Management Engineering, University of Calabria, 87036 Arcavacata di Rende, Italy
Marco Baratieri: Faculty of Science and Technologies, Free University of Bozen-Bolzano, 39100 Bolzano, Italy
Massimiliano Renzi: Faculty of Science and Technologies, Free University of Bozen-Bolzano, 39100 Bolzano, Italy

Energies, 2022, vol. 15, issue 10, 1-19

Abstract: The (partial or total) substitution of petro-diesel with biodiesel in internal combustion engines (ICEs) could represent a crucial path towards the decarbonization of the energy sector. However, critical aspects are related to the controversial issue of the possible increase in Nitrogen Oxides (NO x ) emissions. In such a framework, the proposed study aims at investigating the effects of biodiesel share and injection timing on the performance and NO x emissions of a diesel micro combined heat and power (CHP) system. An experimental campaign has been conducted considering the following operating conditions: (i) a reference standard injection timing (17.2° BTDC), an early injection timing (20.8° BTDC), and a late injection timing (12.2° BTDC); (ii) low (0.90 kW), partial (2.45 kW), and full (3.90 kW) output power load; and (iii) four fuel blends with different biodiesel ( B ) shares ( B0 , B15 , B30 , and B100 ). Experimental data were also elaborated on thanks to the response surface modelling (RSM) technique, aiming at (i) quantifying the influences of the above-listed variables and their trends on the responses, and (ii) obtaining a set of predictive numerical models that represent the basis for model-based design and optimization procedures. The results show: (i) an overall improvement of the engine performance due to the biodiesel presence in the fuel blend —in particular, B30 and B100 blends have shown peak values in both electrical (29%) and thermal efficiency (42%); (ii) the effective benefits of late SOI strategies on NO x emissions, quantified in an overall average NO x reduction of 27% for the early-to-late injection, and of 16% for the standard-to-late injection strategy. Moreover, it has emerged that the NO x -reduction capabilities of the late injection strategy decrease with higher biodiesel substitution rates; through the discussion of high-prediction-capable, parametric, data-driven models, an extensive RSM analysis has shown how the biodiesel share promotes an increase of NO x whenever it overcomes a calculated threshold that is proportional to the engine load (from about 66.5% to 85.7% of the biodiesel share).

Keywords: biodiesel; injection timing; micro-cogeneration; NO x emissions reduction; response-surface methodology (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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