Abstract
The use of primary energy saving techniques and renewable energy systems has become mandatory to tackle the effects of global temperature rise. As a result, a transition is taking place from centralized energy generation to distributed energy generation. Starting from the experience concerning a 15 kW micro-CHP plant previously designed at DII, this paper addresses the development of a 1 kW micro-CHP system fueled by natural gas for single-family users. Specifically, the paper presents a wide experimental investigation aimed at optimizing performance and emissions of a small scale two-stroke spark ignition gasoline engine properly modified to be fueled with natural gas to make the engine more suitable for cogeneration purposes. The described activity was carried out at the DII of the University of Naples Federico II. Rigorous laboratory tests were conducted with the engine in order to characterize both gasoline and CNG operation in terms of brake mechanical power, overall efficiency and exhaust gas emissions in different operating regimes. Furthermore, several physical quantities associated with the engine operation were measured through several sensors in order to optimize performance and emissions achieved when the engine is fueled with CNG. In particular, dynamic pressure variations inside the cylinder were measured and analyzed to evaluate the effect of the adopted fuel on the optimum ignition-timing angle and cyclic dispersion.
Highlights
Anthropogenic carbon dioxide emissions are the most critical issue that must be faced to mitigate the global temperature rise [1]
If the engine speed of 5500 rpm is considered as reference, as it is the operating condition for which the air index is closest and nearly coincident between gasoline and NG equal λ operation (Figure 4), and it corresponds with the maximum thermal efficiency conditions both for gasoline and lean operation
Under the same air–fuel equivalence ratio, the injection of a gaseous fuel like natural gas reduces the incoming air mass flow rate to the cylinder since its specific volume is higher than that of gasoline vapor. This reduction is mitigated in lean burn conditions, while a slight increase in air mass flow rate can be obtained under extremely lean burn operation (Figure 6)
Summary
Anthropogenic carbon dioxide emissions are the most critical issue that must be faced to mitigate the global temperature rise [1]. The novelty of the paper is the performance and emissions optimization of the small scale two-stroke spark ignition gasoline engine on which the 1 kW micro-CHP is based To this aim this engine has been opportunely modified to be fueled with natural gas to make it more suitable for cogeneration purposes and a preliminary comprehensive experimental investigation has been carried out. The use of a low-carbon fuel such as natural gas could provide a substantial reduction of exhaust gas emissions, especially if combined to appropriate and innovative engine operating strategies, in the face of a limited impact on production costs In this scenario, the adoption of a natural gas direct injection system could provide a clean technology that might guarantee a low environmental impact to these types of engines
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
