Research on the Combustion Characteristics of a Free-Piston Gasoline Engine Linear Generator during the Stable Generating Process

Abstract

The free-piston gasoline engine linear generator (FPGLG) is a new kind of power plant consisting of free-piston gasoline engines and a linear generator. Due to the elimination of the crankshaft mechanism, the piston motion process and the combustion heat release process affect each other significantly. In this paper, the combustion characteristics during the stable generating process of a FPGLG were presented using a numerical iteration method, which coupled a zero-dimensional piston dynamic model and a three-dimensional scavenging model with the combustion process simulation. The results indicated that, compared to the conventional engine (CE), the heat release process of the FPGLG lasted longer with a lower peak heat release rate. The indicated thermal efficiency of the engine was lower because less heat was released around the piston top dead centre (TDC). Very minimal difference was observed on the ignition delay duration between the FPGLG and the CE, while the post-combustion period of the FPGLG was significantly longer than that of the CE. Meanwhile, the FPGLG was found to operate more moderately due to lower peak in-cylinder gas pressure and a lower pressure rising rate. The potential advantage of the FPGLG in lower NO x emission was also proven with the simulation results presented in this paper.

A Free-Piston Linear Generator Control Strategy for Improving Output Power

“…The piston motion trajectory is decided by the resultant force acting on the piston [30][31][32][33]. The force analysis is shown in Figure 3.…”

A Decoupled Design Parameter Analysis for Free-Piston Engine Generators

“…As a result, the mover coupled with two pistons reciprocates between its two dead centres, and the linear electric generator converts this mechanical energy into electrical energy. More details on the prototype and its development approach can be found in our previous publications [3,5,[30][31][32].…”

Fundamental Analysis of Thermal Overload in Diesel Engines: Hypothesis and Validation

“…Other key drivers for engine development are low specific fuel oil consumption, which influences the direct operating costs of a ship, and environmental legislation limiting the level of harmful pollutants from diesel engines [2][3][4][5][6]. Rising fuel prices and enforcement of the legislation limiting the NO x and SO x from marine diesel engines have made these drivers more important [7][8][9][10]. A reduction in the fuel consumption can be achieved by running the cylinder hotter, operating closer to stoichiometric conditions where cycle temperatures are higher, and increasing the volume expansion ratio to extract more work for a fixed heat input.…”