Adrian Chmielewski

Research Study of the Micro Cogeneration System with Automatic Loading Unit

This article presents the test bench research of a micro cogeneration system with the Stirling engine with an automatic loading system. The tests were conducted for nitrogen as a working gas. The work presents the influence of the load current on the change of the working gas pressure in the working chamber and on the changing voltage on the electric machine. A significant number of repetitions allowed for a statistical rendering of the research description with the use of such measures as: kurtosis, coefficient of variation, coefficient of asymmetry, and of the function of the probability density. The research allows for determining whether the conducted experiment is reproducible and how the chosen parameters influence the character of the system’s work.

Chosen properties of a dynamic model of crankshaft assembly with three degrees of freedom

In the work presented herein the dynamic model of the crankshaft assembly with three degrees of freedom has been presented. On the basis of the physical model analysis (with the static mass reduction) the simulation model of the crankshaft assembly using Matlab&Simulink programme, has been designed. On the basis of the derived equations of motion, the authors have analysed the influence of chosen parameters, among others: the moment of flywheel inertia, loading torque, different crankshaft rigidity values, on the operation of the simulation model, whose input parameters reflect the real-life crankshaft assembly employed as the working mechanism in the Stirling engine. As a result of the performed simulations, displacement curves, piston velocity and acceleration values, as well as adequate crankshaft angular displacement, the angular velocity and angular acceleration have been additionally presented. The presented results provide information about the dynamic performance of the simulated real-life object.

Research on a Micro Cogeneration System with an Automatic Load-Applying Entity

The article concerns the testbed research of a micro cogeneration system based on a Stirling engine equipped with an automatic load-applying system. The article presents the influence that the load current has on acceleration of vibration of a micro cogeneration system’s body. The research was conducted while using nitrogen as the working gas. Significant number of tests offered the possibility of providing the description of the results in statistical terms while using such measures as kurtosis, coefficient of variation, the asymmetry coefficient as well as the probability density function. The research offers the possibility of concluding whether the completed experiment is repeatable as well as for determining the impact that selected load changes have on acceleration of the micro cogeneration system’s vibration.

Selected Properties of the Dynamic Model of the Piston-Crankshaft Assembly in Stirling Engine Combined with the Thermodynamic Submodel

This work presents a dynamic model of the piston-crankshaft assembly of the Stirling engine with three degrees of freedom combined with the isothermal thermodynamic submodel. The model allowed for consideration of the working gas pressure from the thermodynamic submodel, whose working space was divided into partial volume units and subjected to analysis. Performing the analysis of the physical model and adopting the data from the real object, with the assumption of the static mass reduction, enabled developing of a simulation model of the piston-crankshaft assembly. Subsequently, the model was extended by the part describing pressure changes in the cylinder, theoretical work, theoretical power of the working gas with the assumption of the isothermal heat exchange in the compression and expansion spaces. On the basis of the motion equations shown in the work, the influence of the model’s chosen parameters on the operation of the integrated simulation model was presented and analyzed. The results of the conducted simulations were also additionally derived from an analysis of the displacement, velocity, and piston acceleration curves, as well as the curves of displacement, velocity, and crankshaft angular acceleration. The presented results convey the information about the dynamic operation of the simulated real object working at the preset thermodynamic parameters of the working gas.

Selected properties of the adiabatic model of the Stirling engine combined with the model of the piston-crankshaft system

This work presents the ideal adiabatic model of the Stirling engine which was combined with the dynamic model of the piston-crankshaft system with three degrees of freedom. On the basis of the conducted thermodynamic analysis for the working space in the Stirling engine, and on the basis of the physical model of the working mechanism (constructed with the assumption of the static mass reduction), a multidomain simulation model has been developed, using the Matlab&Simulink software. On the basis of the derived equations of energy conservation for the thermodynamic model, as well as equations of motion for the mechanical model, the influence of chosen thermodynamic and mechanical parameters have been analysed, among others: influence of the temperature of the upper heat source on the theoretical work and power gain, of the temperature changes in the compression and expansion space in the course of the working cycle on the simulation model behaviour, whose input parameters correspond to the real object - the Stirling engine. As a result of the performed simulations, additionally: the flow of the working gas mass at the control borders, and the influence of the transient states on the pressure curve were presented among others. The results discussed in this work convey practical information about the thermodynamic and dynamic properties of the simulated real object.

Dynamic model of a free-piston Stirling engine with four degrees of freedom combined with the thermodynamic submodel

The work presents a dynamic model of the Stirling engine with a free piston, which was combined with a thermodynamic model taking into account isothermal heat exchange in the compression and expansion spaces. On the basis of the performed thermodynamic analysis for the Stirling engine working space, and of the physical model of the system with a free piston, a multidomain simulation model was developed, using the Matlab&Simulink software. On the basis of the derived equations of energy conservation for the thermodynamic model and equations of motion for the mechanical submodel, the influence of the selected thermodynamic and mechanical parameters, including: the influence of the mass of the displacer and piston on the p(V) closed-loop diagram was analysed and the influence of the thermodynamic parameters, including: temperature of the upper heat source on the theoretical work gain and the theoretical work. As a result of the conducted simulations, flow of the working gas mass at the control boundaries and also the curves of the heat fluxes, among other things, were additionally presented. The results presented in this work convey practical information about the thermodynamic and dynamic properties of the simulated object represented by the Stirling engine with a free piston.

Experimental Research of Electrochemical Energy Storage

The paper presents experimental research involving VRLA (Valve Regulated Lead Acid) AGM (Absorbed Glass Mat) batteries. Test-bench research was conducted in the conditions of constant load current. The paper presents the temperature increase on the battery’s terminals and body accompanying battery discharge in the conditions of a preset ambient temperature. The paper also presents the influence that various discharge current values had on growth of the temperature recorded on the battery’s terminals as well as the change of voltage on the battery’s terminals. Furthermore, the paper includes examination of the influence that changes of ambient temperature have on change of a battery’s useful capacity. The influence of the changes of ambient temperature was examined in a climatic chamber. Change of the battery’s internal resistance and the electromotive force, depending on the level of battery charging, are also presented. The analyses were conducted for a typical operating range of a electrochemical battery.

The Use of Fuzzy Logic in the Control of an Inverted Pendulum

Fuzzy logic control is an example of the type of developing the control algorithms using softcomputing, reflecting the imperfections of the real world. The main principle of this type of programming and, therefore, fuzzy logic is to use uncertainty and a part of the truth hidden in the received information in order to achieve the stability and the shortest possible time and simplicity of the implementation. The paper presents an example of using the fuzzy controller in order to maintain proper control of an inverted pendulum. Prepared model of an inverted pendulum pivotally mounted on a carriage represents a nonlinear dynamic object with two degrees of freedom. Control of the system is accomplished by force extortion of the corresponding displacement of the carriage. On the basis of derived equations of motion, the dynamic model of the system in Matlab/Simulink was prepared. At the stage of building a fuzzy controller, they proposed input and output linguistic variables with the respective functions of belonging and base rules. In this paper, the results of a simulation operation of the system of fuzzy logic were presented. Also the advantages and disadvantages of the proposed control method were discussed.

Experimental Research and Simulation Model of Electrochemical Energy Stores

The first part of the paper presents the results of experimental research involving VRLA (Valve Regulated Lead Acid) AGM (Absorbed Glass Mat) batteries, the lithium-ion batteries and lithium iron phosphate (LiFePO4) batteries. The experimental research was conducted in a static cycle (with constant load current). The paper presents the temperature increase on the battery’s terminals and body. The influence that various values of discharge current have on growth of temperature and change of voltage on the battery’s terminals is also presented. The second part of the paper contains the analytical relations which have been used for building the simulation model in the MATLAB&Simulink environment. The results obtained on the basis of the model have been validated against the results of experimental research.

Experimental Evaluation of Mathematical and Artificial Neural Network Modeling of Energy Storage System

This article presents an experimental evaluation based on a mathematical model and an artificial neural network (ANN) model of an energy storage system. Because of a nonlinear description of charging/discharging dynamics in subsequent cycles and a coupling of the terminal voltage and temperatures of a battery, the recurrent artificial neural network structure (R-ANN) is proposed. Both models, analytical and R-ANN were employed to predict a behavior of the VRLA AGM battery. A training and testing data were gathered at the laboratory stand in different working conditions. As a result, we present the analysis of differences between proposed modeling approaches.