Adam Polak

Simulation Model of PEM Fuel Cell Operating at Hydrogen and Oxygen

Effective control of a fuel cell requires a proper mathematical model. Plenty of completely described models of PEM fuel cells operating on hydrogen and air are to be found in the literature. However, there is a lack of the models for the PEM fuel cells operating on pure hydrogen and oxygen. The paper proposes a static model of such an energy source. Parameters of the model are determined by the Genetic Algorithms using experimental data gathered during operation of the real hydrogen/oxygen PEM fuel cells stack.

Fuel Cells for Autonomous Underwater Vehicles

A long-distance performance is a significant parameter for mobile platforms. A key condition is a highly efficient source of energy. Fuel cells, i.e. electrochemical devices, capable of direct conversion of chemical energy accumulated in fuel into electrical energy, occurred to be relevant. In this paper there were presented the results of the analysis pertaining to the volumetric requirements of the system exploiting the fuel cell that is capable of ensuring the running time comparable with that of conventionally used rechargeable batteries.

Implementation of the assessment method of the lead–acid battery electrical capacity in submarines

Lead–acid batteries are still being used in conventional submarines as the primary source of power. Due to their properties, lead–acid batteries require a lot of attention during their operation, including charging according to fairly rigorous rules. Because of their special operating conditions in submarines, it is not possible to maintain optimal conditions for such batteries. The battery’s integrated management system allows for remote and online monitoring. However, it gives only general information about how much energy remains in the battery for use in operating conditions. The submarine’s operational capabilities, such as range and operation time, depend to a great extent on battery capacity, so information of its condition and status is very important. The proposed method of evaluating the capacity of lead–acid batteries allows them to be processed during their exploitation, without the need for a time-consuming and expensive capacity test. The measurements needed to implement the proposed algorithm are already implemented in the existing battery monitoring system – no additional equipment is required. Based on the results of the proposed method, it will be possible to easily determine how much energy is available to the submarine, which is crucial in planning combat missions at the sea.

The parameters of excitation current of ship synchronous generator as the diagnostic symptoms of the propelling IC engine

ABSTRACT For ships, the total loss of electrical power, ‘blackout’, is a critical failure. The failure of the marine power supply system not only results in loss of ability to perform tasks, but also poses a threat to human life and often to the environment. No less serious emergency is ‘partial blackout’, i.e. the loss of electricity in parts of the electrical system. Designers are introducing technical and system solutions to minimise the likelihood of power failure and to support its recovery in a timely manner. One of the methods to minimise the likelihood of power failure is to identify and then monitor diagnostic symptoms that are susceptible to approaching the failure of key components of the power system. This article discusses the use of recording and analysis of changes in voltages and excitation currents in parallel synchronous generators to determine the threshold above which their parallel operation can lead to an emergency power failure.

Influence of cathode stoichiometry on operation of PEM fuel cells’ stack supplied with pure oxygen

ABSTRACT As a part of ongoing research into the use of fuel cells to power underwater platforms, studies have been conducted to investigate the effect of change in oxygen flow through the proton exchange membrane fuel cell (PEM-FC) cathode channel, to develop a method for controlling this flow. Due to the lack of specific information or studies on the effect of pure oxygen flow through the PEM-FCs cathode channel on the correctness of its work, a series of experiments have been carried out within the framework of in-house research to determine this dependence. The experiment was conducted in series, during which the only change in the operating parameter of the PEM-FC stack was the stoichiometric flow rate of oxygen supplied to the cathode channel of the fuel cells’ stack. The research shows that for the PEM-FCs stack fed with pure oxygen, the cathode stoichiometry can be kept at a much lower level comparing to the systems supplied with air. It has been found that the fuel cells’ stack fed with pure oxygen will perform well in steady state while reducing the cathode stoichiometry by as much as 40% compared to systems utilising oxidant from atmospheric air.

Piecewise Control Method of Oxygen Flow in PEM Fuel Cell

The paper presents a method of control of an oxygen flow in the PEM fuel cell without recirculation. The proposed procedure of finding an optimal value of the oxygen flow basis on comparing a current voltage of the cell with a reference one obtained from a static model of the PEM fuel cell. Simulation results show that such value of the flow is obtained for a limited number of steps. It allows to reduce the oxygen usage assuring safe operation of the fuel cell.

Integration of PEM Fuel Cells and Lithium Ion Secondary Battery into a Single Hybrid Electric Energy Source – Part I: Control System

Both fuel cells and lithium-ion cells are chemical sources of electric energy. In either of these sources, energy is obtained from chemical reactions performed at the electrodes. However, different constructions of those cells causes that they are characterized by different, and in many cases opposite, properties. Their combination into a single hybrid power source can therefore lead to utilization of advantages of both of them and, at the same time, mutual elimination of their disadvantages. The article presents control assumptions, structure of control system and control algorithm of a hybrid portable electric energy source in an early stage of development – a technology demonstrator. Discussed technology demonstrator integrates PEM fuel cells with Li-ion secondary cells.

Concept of Measurements and Acquisition System for Identification Process of a Synchronous Ship Generator

The process of identification of the parameters of a mathematical model of any dynamic real object necessitates performing the relevant number of measurements with the accurate precision of the quantities that characterize the current temporal state of this object (i.e. object’s vector of state). The accurate identification of the parameters of such a model is achievable only with the help of an especially designed system of acquisition and measurement. This article describes the mathematical model of ship’s synchronous generator with the presupposed simplifications, the parameters of this model and the methods of its determining. There is also presented the conception of the system of acquisition and measurement (based on CompactDAQ platform produced by National Instruments), which is indispensable for identifying the parameters of this model.

Experimental Studies of Direct Cooperation of PEM Fuel Cells and Secondary Batteries

Fuel cells and secondary batteries have both some disadvantages and advantages. However, looking closer at their characteristics, it can be concluded that in various aspects fuel cells and secondary batteries complement each other. Thus, combining these different electric energy sources to make one hybrid electricity source would allow using advantages of both sources and eliminating their disadvantages. In this article there are presented a comparative characteristic of PEM fuel cells and secondary batteries, their configuration of cooperation, and experimental results of their direct cooperation.