Abstract
The current energy transition and its future prospectives represent a crucial path for scientific research. Due to its broadness and its influence on difference fields of everyday life, researchers and technicians with different backgrounds are struggling to tackle challenges related to the energy issue. The proposed work fits in such framework and finds its motivations into three main challenges: i) the not-renewable nature of fossil fuels primary sources and its socio-economical consequences dealing with fluctuating costs of raw materials ii) the globally growing energy demands and the spread of energy poverty iii) the environmental issues related to the use of fossil fuels. The main hypothesis behind the proposed work is that current energy technologies will still be strongly available in the market in the next future: a large part of population will be relying on such technologies. Given this assumption, the used approach wants to represent a way to apply technical innovations to actual, solid and reliable, energy conversion technologies. The research work aims at investigating micro combined heat and power generation - CHP - systems able to substitute fossil fuels with alternative ones, both liquid and gaseous. Hence, a test rig based on a Diesel engine has been developed and realized in the laboratory of the Free University of Bolzano. Two experimental campaigns have been realized, a first one aimed at substituting diesel with biodiesel and bioethanol mixtures and a second one focused on the use of forestry biomass producer gas as a diesel substitute. Performances and emissions characterizations have been realized in both cases. Moreover, the study proposes a thermodynamic modelling approach of dual fuel producer gas-diesel combustion as well as a technical experimental and numerical investigation on the limits of the use of biofuels in compression ignition engines on auxiliary devices. The purposes of the proposed research activities are to enrich the technical and scientific knowledge in the field of micro-CHP systems fueled with biofuels. The innovative outcomes of the work deals with: i) the investigations of micro-scale (0 − 4 kW) CHP electrical power output ii) the use of bioethanol as additive for diesel/biodiesel blends, as a way to boost both environmental and energy performances of the system iii) the proposed test rig that couples a downdraft open top biomass gasifier with a diesel engine to realize a micro-CHP system iv) producer gas-diesel system characterization results, especially in terms of exhaust emissions.