CONTROL SYSTEM PREVENTING THERMAL GRADIENT DEVELOPMENT ON FOILS OF FOIL BEARING

This article presents attempts at automating a control system to reduce temperature scatter on the foil of a foil bearing. The control system reads the temperatures at six circumferential locations of the bearing’s foil and distributes control currents to the thermoelectric modules integrated into the bearing’s bushing. Three basic approaches have been proposed and tested: 1) a simple hot-spot tracking algorithm assigning predefined current values to the modules closest to the hot-spot location; 2) a tracking algorithm reducing abrupt changes in the control currents and, in effect, the local heat flux distribution; and 3) a tracking algorithm enhanced with a PID controller. The proposed controller has been implemented and compared to the performance of a temperature controller that does not have tracking capabilities. The implemented control strategies have proven the feasibility of temperature scatter reduction inside the investigated bearing. In most test cases, the instantaneous gradient reduction exceeded 50% (reaching 63% at its best)

RESTORING THE PASSIVITY OF SHUNT DAMPING CIRCUITS BASED ON THE SYNTHETIC INDUCTANCE BY THERMAL ENERGY HARVESTING

For decades people have used ambient energy, e.g., that of rushing streams or wind to obtain usable power. Starting with very low energy conversion, through constant development we have now reached the stage of extensive possibilities of harvesting the energy from the environment we live in. Today, there exist almost unconstrained opportunities to energize a broad spectrum of devices by energy available almost anywhere and of whichever form. One of the great advantages of energy harvesting is to make small electronic devices autonomous eliminating the need ofpower supply and mainte­nance. Shunt damping systems are unfavorably influenced by the size and mass of the coil inductors. While substituting bulky inductors with synthetic inductors one losses the passivity of the system gaining its practicability. Nevertheless, in order to outperform the actively driven systems, it is indispensable to return the passive properties of the system maintaining its performance. This paper presents the feasibility study ofpowering the passive shunt damping devices by the work that is lost irrevocably in a bearing node. The heat generated in a bearing is converted via the thermoelectric phenomenon and then used to power the synthetic inductance circuitry. In the paper it is shown that the required power levels can be satisfied by the thermoelectric generator paired to a moderately loaded bearing

The effect of cooling the foil bearing on dynamics of the rotor-bearings system

In order to protect rotors and foil bearings operating at high temperatures from being overheated and damaged, these components are often cooled by air. In addition, such a cooling method is accompanied by an axial temperature gradient that changes the shape of the lubrication gap in a way likely to affect the operation of a foil bearing. This article presents the research on various methods for cooling a foil bearing and discusses the impact of these methods on dynamic parameters of the rotor-bearings system. To be able to assess the temperature inside such a bearing, there is a need for a reliable measurement method. The authors of the article measured the temperature of the top foil using thermocouples and showed that their measurement method does not exert any significant impact on the operation of the rotor-bearings system. The article also describes a novel method for compensating the axial temperature gradient occurring in the bearing bush using Peltier modules

Smart structures and materials in energy harveting in a bearing node of a rotating machinery : PhD dissertation /

Recenzenci pracy: Krzysztof Mendrok, Jan Kiciński.Praca doktorska. Akademia Górniczo-Hutnicza im. Stanisława Staszica (Kraków), 2012.Bibliogr. k. 110-118.Review of energy harvesting methods from heat sources, vibration damping methods via shunted piezoelectrics, thermoelectricity, Thermoelectric Energy Harvesting, Analytical Models, circuit models, Finite Element Method, adopted approach, piezoelectricity, Piezoelectric Shunt Damping Technique, adopted approach, energy harvesting possibilities in a bearing node, models of applied subsystems, Thermoelectric Generator, TEG, Heat Sink, Convective Heat Transfer at Rotating Shaft, Bearing Power Loss, sensitivity, circuit analysis, continuous operation mode, burst operation mode, concept of the vibration damper powered via the thermal harvesting source, proof of concept, numerical assessment of expected system performance, Numerical Approach in Assessing the Shunted Piezoelectric Damping Capabilities, Proposed Calculation Scheme, auxiliary test case, experimental verification, verification of impedance method implementation, for coupled FSI analysis, passenger test car, real world example of application the proposed numerical procedure, Problem Description, Numerical Analysis, analysis of results, applicability study, bibliometrics, schematic view of the harvesting circui

Restoring the passivity of shunt damping circuits based on the synthetic inductance by thermal energy harvesting Przywrócenie pasywnego charakteru metodzie tłumienia drgań opartej o materiały piezoelektryczne przez wykorzystanie techniki pozyskiwania energii strat cieplnych /

Tyt. z nagłówka.Bibliogr. s. [29].Od zawsze ludzie wykorzystywali energię dostępną w ich otoczeniu i przekształcali ją w użyteczną pracę mechaniczną. Stopniowo priorytetowym zadaniem stało się pozyskiwanie energii w formie energii elektrycznej. Z początku niewielka sprawność i koszt inwestycyjny nie pozwalał na szerokie wykorzystanie technik pozyskiwania energii, dzisiaj stajemy przed niespotykanym wcześniej zapotrzebowaniem na energię, a przede wszystkim mamy możliwość generowania energii ze źródeł różnego typu i wielkości dostępnych w naszym otoczeniu. Technika pozyskiwania (zbierania) energii oferuje szeroki potencjał możliwości zasilania urządzeń elektronicznych małych mocy, przekształcając je w jednostki autonomiczne niewymagające zasilania ani okresowej wymiany magazynu energii. Technika tłumienia drgań z wykorzystaniem materiałów piezoelektrycznych ograniczona jest przez wymaganą synchronizację drgań konstrukcji i obwodu rezonansowego, która niesie za sobą konieczność użycia cewek indukcyjnych o znacznych wymiarach gabarytowych i masie. Istnieje możliwość zastąpienia tych elementów przez sztuczną indukcyjność realizowaną jako układ elektroniczny za pomocą wzmacniaczy operacyjnych kosztem utraty pasywnego charakteru metody. W artykule zaprezentowano studium wykonalności układu tłumienia drgań wykorzystującego sztuczną indukcyjność, ale zasilaną ze źródła energii pozyskiwanej ze strat cieplnych łożyska. Artykuł udowadnia, że dla szerokiego spektrum przypadków połączenie techniki pozyskiwania energii oraz techniki wykorzystujących bierne obwody (shunt damping) jest korzystne.For decades people have used ambient energy, e.g., that of rushing streams or wind to obtain usable power. Starting with very low energy conversion, through constant development we have now reached the stage of extensive possibilities of harvesting the energy from the environment we live in. Today, there exist almost unconstrained opportunities to energize a broad spectrum of devices by energy available almost anywhere and of whichever form. One of the great advantages of energy harvesting is to make small electronic devices autonomous eliminating the need of power supply and maintenance. Shunt damping systems are unfavorably influenced by the size and mass of the coil inductors. While substituting bulky inductors with synthetic inductors one losses the passivity of the system gaining its practicability. Nevertheless, in order to outperform the actively driven systems, it is indispensable to return the passive properties of the system maintaining its performance. This paper presents the feasibility study of powering the passive shunt damping devices by the work that is lost irrevocably in a bearing node. The heat generated in a bearing is converted via the thermoelectric phenomenon and then used to power the synthetic inductance circuitry. In the paper it is shown that the required power levels can be satisfied by the thermoelectric generator paired to a moderately loaded bearing.Dostępny również w formie drukowanej.SŁOWA KLUCZOWE: metoda tłumienia drgań, materiały piezoelektryczne, pozyskiwanie energii strat cieplnych. KEYWORDS: shunt damping circuits, thermal energy harvesting

Sensitivity analysis of a municipal wastewater treatment plant model

Waste management is a crucial process to keep the environment in wholesome conditions. The environmental impact of solid waste and wastewater is reduced through construction of appropriate disposal installations. The objective of wastewater treatment in biological reactors is to control the process of biomaterial growth by aerating the sewage content. The process is complex, as depending on a plenty of parameters. In the last decades an effective numerical model, called the Activated Sludge Model (ASM), has been proposed for describing the biological process. The ASM is implemented in the Benchmark Simulation Model (BSM) that simulates the whole wastewater treatment process. The most important parameters in ASM are the kinetic and stoichiometric coefficients. The former describes rate-concentration dependence. The latter characterises the relationship between the components of chemical reactions taking place in the cleaning process. Above parameters are determined by on-site calibration and their importance is relevant during the development of numeric models. This paper aims to examine the influence of kinetic and stoichiometric parameters on the wastewater treatment process of a plant in Płaszów, Kraków. The analysis is carried out by a sample-based numerical procedure. It highlights the ASM parameters playing a major role in the treatment process. Results obtained from the analysis are important for future validation and optimisation processes

Sensitivity analysis of a municipal wastewater treatment plant model

Waste management is a crucial process to keep the environment in wholesome conditions. The environmental impact of solid waste and wastewater is reduced through construction of appropriate disposal installations. The objective of wastewater treatment in biological reactors is to control the process of biomaterial growth by aerating the sewage content. The process is complex, as depending on a plenty of parameters. In the last decades an effective numerical model, called the Activated Sludge Model (ASM), has been proposed for describing the biological process. The ASM is implemented in the Benchmark Simulation Model (BSM) that simulates the whole wastewater treatment process. The most important parameters in ASM are the kinetic and stoichiometric coefficients. The former describes rate-concentration dependence. The latter characterises the relationship between the components of chemical reactions taking place in the cleaning process. Above parameters are determined by on-site calibration and their importance is relevant during the development of numeric models. This paper aims to examine the influence of kinetic and stoichiometric parameters on the wastewater treatment process of a plant in Płaszów, Kraków. The analysis is carried out by a sample-based numerical procedure. It highlights the ASM parameters playing a major role in the treatment process. Results obtained from the analysis are important for future validation and optimisation processes