Zbigniew Kneba

Causality in Models of Thermal Processes in Ship Engine Rooms with the Use of Bond Graph (BG) Method

Abstract With a single approach to modeling elements of different physical nature, the method of Bond Graph (BG) is particularly well suited for modeling energy systems consisting of mechanical, thermal, electrical and hydraulic elements that operate in the power system engine room. The paper refers to the earlier presented [2] new concept of thermal process modeling using the BG method. The authors own suggestions for determining causality in models of thermal processes created by the said concept were given. The analysis of causality makes it possible to demonstrate the model conflicts that prevent the placement of state equations which allows for the direct conduct of simulation experiments. Attention has been drawn to the link between the energy systems models of thermal processes with models of elements of different physical nature. Two examples of determining causality in models of complex energy systems of thermal elements have been presented. The firs relates to the electrical system associated with the process of heat exchange. The second is a model of the mechanical system associated with the thermodynamic process.

The Possibility of Co-Combustion of Gaseous Fuel in Compression Ignition Engines

The article presents an analysis of the possibilities of co-combustion of two fuels in truck diesel engines. The goal of usage two different fuels is to lower coast of exploitation heavy duty trucks and buses. The two systems were introduced In first the ignition in cylinder is initiated by diesel oil small dose then main dose of methane is burned. In the alternative system the share of diesel oil is much greater and the mixture of propane butane is only additional fuel. Measurement results of first inwestigations has been presented. The important remarks about setting pilot injection dose and injection time angle were munched.

A Model of Thermal Energy Storage According to the Convention of Bond Graphs (Bg) and State Equations (Se)

Abstract The main advantage of the use of the Bond Graphs method and State Equations for modeling energy systems with a complex structure (marine power plants, hybrid vehicles, etc.) is the ability to model the system components of different physical nature using identical theoretical basis. The paper presents a method of modeling thermal energy storage, which is in line with basic BG theory. Critical comments have been put forward concerning multiport energy storage introduced by other authors or the so-called C-field. In suggested approach, the decision not to use pseudo Bond Graphs has been justified as not being in line with basic BG theory. On the basis of molecular physics it was considered that the state variable, in physical and mathematical sense, should be temperature rather than entropy. Examples of the application of the proposed approach to thermodynamic processes and heat exchange have been presented. The application of a single graph as a model for thermal energy storage has been illustrated by a way of numerical simulation examples.

The Initial Selection of Parameters for Dynamic Brake for Car Engine Test Dynamometer

The article presents an analysis of the car engine loads. The aim of the analysis was to determine the parameters of the brake / electric motor on an engine test bad. Analysis of loads on the driving tests concerned on chassis dynamo to simulate them on an engine dynamometer. To check the range of dynamometer shaft angular acceleration inertial mass of a car was reduced on the crankshaft axis. The calculations of maximum shaft acceleration were performed. Also the whole car acceleration when pulling away from the place was calculated. Calculations were verified by experiment on road. They both gave a good agreement.

Carbon Dioxide Potential Reduction Using Start-Stop System in a Car

Operating fuel consumption increases significantly when the vehicle stops frequently while driving or when the engine is idling during braking. In such cases, the internal combustion engine consumes the fuel but the mechanical energy is not used by the drive system. The amount of fuel that is consumed in this time by the engine can potentially be saved if the car is equipped with a Stop-Start system. Start-Stop system automatically shuts down and restarts the internal combustion engine due to strategy used by controller reducing this way toxic compounds emissions in exhaust gasses and the fuel consumption, which is directly connected to carbon dioxide (CO2) emissions. The paper presents an analysis of the potential reduction in CO2 emissions for selected vehicles with Start-Stop system during operation in selected urban agglomeration using different strategies to control this system. The study was carried out using numerical models of propulsion systems. The results were compared with the statistical data derived from regular use of vehicles equipped with such a system.

Rigid Finite Element Modeling for Identification of Vibrations in Elastic Rod Driven by a DC-Motor Supplied from a Thyristor Rectifier

The paper deals with the numerical analysis of electromechanical systems. The system consists of a DC motor supplied from a half-wave, single phase, thyristor rectifier, and of a flexible rod fixed to the axis of armature. Discretization of rigid segments is used to model flexibility of the rod. The discrete structure is considered as a multibody system, i.e. as a single kinematical chain of rigid bodies connected by massless joints. Significant drift rotation is included in the rod model. Numerical integration is performed in order to predict behavior of the system. Two working conditions are tested: steady-state motion and transient braking of the system. The attention in the paper is concentrated on interactions between the mechanical and electrical systems.