R. Lanzafame

Water Injection Effects In A Single-Cylinder CFR Engine

Though analysed by a few researches, the practice of water injection in Spark Ignition Engines (SI-ICE) does not yield homogeneous results, owing to various typologies of engines used for experiments. In this paper the effects of water injection in the intake pipe are investigated from both a theoretical and experimental viewpoint. Pressure vs. time diagrams were recorded on a single-cylinder CFR engine at AGIP PETROLI, Priolo (CT). Tests were performed according to Research and Motor Method (ASTM). Water was supplied by a continuous injection system inclusive of comparatively high pressure pump. The engine was fed with low O.N. base gasoline (cheap products, intermediate of refinery processes). The water to fuel mass flow rate ratio was varied in the range 0 to 1.5. The NOx emissions measurements confirm the tremendous effectiveness of water injection in reducing the engine environmental impact. Test data have been used to implement a detonation model that allows to predict water injection effects. Results have shown that water injection really represents a new way to avoid detonation, to reduce compression work and to control NOx formation in SI engines.

Field Experience With Performances Evaluation of a Single-Crystalline Photovoltaic Panel in an Underwater Environment

In this paper, the electrical and thermal performances of a single-crystalline submerged photovoltaic (PV) solar panel (SP2) is investigated. In particular, due to the presence of water, several phenomena occur such as the modification of solar-radiation spectrum and the reduction of the module operating temperature. These phenomena have different impacts on the global energy performance of the PV module, which depends on the environmental conditions, on the PV technology, and on the water depth. Energy performances of an SP2 module are measured using two different experimental setups in different environmental conditions, with an increase in power ranging from 10% to 15%.

OPTIMAL WIND TURBINE DESIGN TO MAXIMIZE ENERGY PRODUCTION

Abstract Determining the best geometric parameters for the blade of a wind turbine is critical for maximizing energy production. This paper considers how to determine the laws which govern twist to maximize electrical energy output for a rotor with two blades, with a 10 m diameter, in a given wind site. Optimum twist was obtained by applying the ‘blade element momentum theory’. Then two different blade design methods were compared. The first, based on maximizing the power coefficient (at the average wind velocity, assuming an attack angle which maximizes the ratio of lift and drag coefficients); the second, based on maximizing the annual energy production for the turbine object of this study, in a given wind site.

A new method for the calculation of gases enthalpy

In this paper, the authors have investigated new polynomial functions for the determination of enthalpy for various gases, and for their mixtures, in ICE applications. Several polynomial functions have been investigated to determine the best matching function with respect to experimental data. Functions investigated are: exponential polynomials and logarithmic polynomials (third, fourth and fifth order). The best polynomial functions have the functional form of a V order logarithmic polynomial, and can be used in temperature ranges of practical interest. Logarithmic polynomial (LP) coefficients have been obtained by least squares matching with thermodynamic property data from the JANAF tables. Values of the specific heat have been calculated as a function of temperature, and they have been compared with experimental ones, in order to evaluate the percent error. Logarithmic polynomials (LPs) have been calculated for various gases: technical air (21% O/sub 2/), N, O, H, H/sub 2/, O/sub 2/, N/sub 2/, CO, OH, NO, CO/sub 2/ and H/sub 2/O. In literature there are many works which present mathematical functions of enthalpy vs temperature. A comparison between the polynomial functions that are present in literature and V order LP has been effected. The new LPs point out a major precision respect to the other polynomial functions, and the possibility to utilise a single LP for a wide temperature range, according to a good accuracy with experimental data.

Experimental Data Extrapolation by Using V Order Logarithmic Polynomials

In this work, the authors consider the possibility to extrapolate experimental data on fuels specific heat at constant pressure, beyond the range of temperature investigated in the experimental measurements. With a proper extrapolation it is possible to avoid the necessary but empirical linear extrapolation, often used by CFD programs. Mathematical functions obtained from fitting experimental data are very useful when computational models on ICE are implemented. To obtain reliable results from these models, a great precision is required to the mathematical functions. In this work a new polynomial, used in order to fit experimental data on gases properties at low pressure, is presented. The new mathematical function presented has the functional form of a fifth order Logarithmic Polynomial, and it is evaluated through the least squares method, on the basis of experimental thermodynamic data found in literature. This new function presents three great advantage in respect to traditional polynomials used in literature: 1) it offers a great fitting precision (correlation factor R2 greater than 0.99); 2) it is able to cover wide range of temperature with a single polynomial; 3) it gives the possibility to extrapolate data beyond experimental temperature range.Copyright

Investigation on Realizing Fuel Rate Shaping Using a Common Rail Injector

The present work deals with the first researches into the real capabilities of an electronically controlled injector for common rail systems in realizing a proper shaping of the fuel rate with particular reference to its rising profile. Injectors equipped with standard and geometrically modified control valves have been investigated in detail by means of computer modeling and simulation. Experiments have been carried out in order to validate the feasibility of such a shaping and the injection rate meter based on the method proposed by Bosch was used. The main result of this work is a noteworthy dependence of the fuel rate on geometrical modifications in the piloting stage of the injector, since a certain difference in the slope of the first part of the fuel rate has been attained. The injector model has been finally used to investigate further geometrical modifications to be realized in order to achieve the desired fuel rate shaping.Copyright

Equilibrium Thermodynamics of Combustion by Means of Genetic Algorithms

In order to carry out an accurate heat release analysis, it is necessary to solve a non linear set of chemical equilibrium equations to calculate concentrations of the species present in cylinder gases during the combustion process. So, the thermodynamics properties of the mixture can be evaluated. The present paper deals with the study of the thermodynamics of combustion using a genetic approach. A genetic algorithm was used to solve the set of non linear equations. The goal of this method is the possibility of solving the equations set in a wide range of pressure, temperature and equivalence ratio combinations, where more traditional methods are often found to fail.Copyright

On the Pressure Relief Valve for the Lubrication System of an Internal Combustion Engine

The lubrication system for automotive internal combustion engines consists of several components. Oil flow rate for lubrication is generated by a positive displacement pump equipped with a pressure relief valve, usually present in the casing of the pump to prevent high oil pressures building up in the system and to deliver to the sump the exceeding generated flow rate. This study focuses on the static and dynamic characteristics of the pressure relief valve with considerations about the stability of the overall system, according to design parameters of both the valve and the system itself.Copyright

On the Combustion Turbine Modeling: A Dynamic Approach

The present paper deals with the dynamic analysis of a heavy duty combustion turbine running on natural gas. Hence, a mathematical model of the power plant has been implemented. The model is able to simulate the engine behavior during steady state, as well as transient conditions. In order to test the model efficacy and accuracy, a dynamic analysis of a Siemens V94.3 A running as topper in a Combined Cycle (CC) complex has been carried out. Therefore, numerical results have been compared with experimental data extracted from the monitoring system of the plant for different running conditions. Comparison results analysis highlighted that the developed mathematical model is able to simulate correctly engine behavior in different combustion turbine conditions.© 2007 ASME

The Influence of Specific Heats Variability on Heat Release Analysis Using Two-Zone Models

Heat release and burn rate analysis in Internal Combustion Engines (ICEs) are usually based on a zero-dimensional application of First-Law of thermodynamics. In order to evaluate the heat release models available in literature use the differential form of the energy conservation equation, generally neglecting specific heats derivative terms. In this work the effects of specific heats derivative terms on a two-zone heat release model, for a Spark Ignition (SI) engine, have been evaluated. Results obtained with and without considering specific heats derivative terms have been compared. These comparisons show that proposed modifications allow to obtain more regular curves especially for mass fraction burned and heat release according to the combustion phenomenology. Besides, taking into account the specific heats derivative terms, the models calibration constants do not need to be tuned, and the combustion efficiency can be evaluated directly by the mathematical model (otherwise experimentally measured).Copyright