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The distributed generation of electricity is worldwide growing thanks to the inherent advantages it brings to local users: in this context, micro-cogeneration systems allow cheap, affordable and reliable power and heating supply. The experimental operation of a 25 kWe Yanmar micro-CHP, based on a 4-stroke, 4-cylinder lean-burn internal combustion engine fed by natural gas exploiting the Miller cycle, during a time period of 1 year is here analyzed. The system is coupled with an absorption chiller and is installed in a small-size enterprise in central Italy, in order to supply the thermal base load of the company and part of the electric request. The main characteristics and the performance of the engine are widely analyzed, in particular the electric and thermal efficiencies are mapped through the whole year and the most remarkable differences due to the seasonal environmental conditions are underlined.

Worldwide, whenever thermal energy is required one of the most common supply solution is represented by the adoption of an electric heat pump. Nevertheless, other solutions may represent a valid option and the use of a Gas Heat Pump (GHP), based on an Internal Combustion Engine (ICE) fed by natural gas, is one of these. The experimental results of the operations of a GHP in a small-size enterprise in central Italy are presented: the test site, with its energy requests and technical constraints is described. Furtherly, a comparison with an electric heat pump is carried out by reproducing its behavior through a 1-D simulation tool developed in the Simulink environment. The advantages that the thermal generator based on the ICE can bring compared to an electric solution from the technical, economic, and environmental point of view are highlighted.

For the development of a very high efficiency engine, the continuous monitoring of the engine operating conditions is needed. Moreover, the early detection of engine faults is fundamental in order to take appropriate corrective actions and avoid malfunctioning and failures. The in-cylinder pressure is the most direct parameter associated to the engine thermodynamic cycle. The cost and the intrusiveness of the dynamic pressure sensor and the harsh operating condition that limits its life-time, make the direct measurement of the in-cylinder pressure not suitable for mass production applications. Consequently, research is oriented on the measurement of physical phenomena linked to the thermodynamic cycle to obtain useful information for the ICE control.

For the development of a very high efficiency engine, the continuous monitoring of the engine operating conditions is needed. Moreover, the early detection of engine faults is fundamental in order to take appropriate corrective actions and avoid malfunctioning and failures. The in-cylinder pressure is the most direct parameter associated to the engine thermodynamic cycle. The cost and the intrusiveness of the dynamic pressure sensor and the harsh operating condition that limits its life-time, make the direct measurement of the in-cylinder pressure not suitable for mass production applications. Consequently, research is oriented on the measurement of physical phenomena linked to the thermodynamic cycle to obtain useful information for the ICE control.

In order to ensure a high level of performance and to comply with more severe limitations in term of fuel consumption and emissions reduction, a continuous supervision of the engine operating conditions, by monitoring several parameters, is needed. The growing use of turbocharger (TC) in ICE for automotive and industrial applications suggests to use the TC speed as a possible feedback of engine operating condition. Indeed, the turbocharger behavior is connected to the thermo-dynamic and fluid-dynamic conditions at the engine cylinder exit: this feature suggests that the turbocharger speed could give useful information about the engine cycle. In previous studies, a preliminary investigation of the relationship between the engine performance and the turbocharger speed of a four-stroke multi-cylinder turbo-diesel engine was carried out by varying the operating conditions of the engine such as fuel mass flow rate, EGR rate and back pressure at the turbine outlet.

A condition monitoring activity consists in the analysis of several information from the engine and the subsequent data elaboration to assess its operating condition. By means of a continuous supervision of the operating conditions the internal combustion engine performance can be maintained at design-level in the long term. The growing use of turbocharger (TC) in automotive field suggests to use the TC speed as a possible feedback of engine operating condition. Indeed, the turbocharger behavior is influenced by the thermo and fluid-dynamic conditions in the cylinder exhaust port: this feature suggests that the TC speed could provide useful data about the engine cycle. In this study the authors describe a theoretical and numerical analysis focused on the TC speed in a four stroke turbo-diesel engine. The purpose of this study is to highlight whether the TC speed allows one to detect the variation of the engine parameters.

The purpose of this work is to perform an analysis on the modifications necessary to convert a four-stroke engine into a non-conventional two-stroke engine. The first aim of this work is to reach the theoretical advantages of the two stroke engine (high torque values at lower rpm and working regularity) and, at the same time, to avoid the usual problems of the two stroke cycle (short-circuit of fresh air-fuel mixture and consequently pollutant emissions and high specific fuel consumption). The target is to develop a small engine with innovative solutions that allows to obtain high performance coupled with good mechanical and thermodynamic efficiency. The starting base engine is a 125cc four-stroke two-valves scooter engine equipped with a volumetric compressor. The idea is to convert it from four to two stroke cycle, using head valves and adding scavenge ports in the cylinder.

The purpose of the study is to develop a flexible simulation tool that allows coupling the 1-D simulation of the engine with the dynamic simulation of the whole vehicle on which the engine is installed, in order to predict vehicle operating conditions and exhaust emissions during an imposed mission profile. In fact 1-D engine simulation can supply information on engine performance but not on vehicle performance, that strongly depends on the vehicle itself. Therefore vehicle performance simulation needs an integrated engine-vehicle approach. The dynamic model of the vehicle (a scooter with CVT transmission) is built up in Matlab-Simulink while the engine model is realized by means of a 1-D commercial code (WAVE, Ricardo Software). In particular, the Urban Driving Cycle (UDC) of the European Community ECE-40 homologation test (established by the EL) directive 2002/51/CE) for a scooter with CVT transmission and centrifugal clutch is the aim of the simulation activity.

The purpose of this study is to create and develop a flexible simulating tool that allows to couple the simulation of the engine, performed by means of a 1-D computer-aided engineering code (WAVE, Ricardo Software), along with the dynamic simulation of the whole vehicle on which the engine is installed. The dynamic model of the vehicle (a scooter with CVT transmission) is realized with Simulink, and is schematized as a rigid body subjected to the engine force, aerodynamics forces, tyres friction forces with an equivalent mass which is the sum of the vehicle mass and the rotating equivalent mass. A complete Simulink model of the CVT transmission is realized too. In the present work the authors want to provide a general methodology that permits to numerically evaluate the performance, the operating conditions and exhaust emissions of an engine once it is installed on a given vehicle.