Wyniki wyszukiwania - BazTech

1

Steady state and transient analysis of solid oxide fuel cell within the framework of thermodynamic energy cycles

Matysko Robert

Archives of Thermodynamics

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2023

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Vol. 44, no 4

317--333

EN

The provided article comprehensively explores the modelling and analysis of solid oxide fuel cell (SOFC) systems within the context of thermodynamic energy cycles. The paper provides insight into various applications of these cells, with a specific emphasis on their role as the primary source of electrical energy in systems that work with biogas and heat recovery. The technological structure of these systems is delineated, with a focus on their principal components and the chemical reactions occurring within SOFCs. Moreover, the article incorporates a mathematical model of SOFCs and presents calculation results that illustrate the influence of air and fuel temperature on the cells’ efficiency. The research indicates that optimal SOFC efficiency is attained at higher temperatures of supplied air and fuel. The presentation of the results of calculations for the solid oxide fuel cell and its thermodynamic cycle, considering fuel supply and its thermodynamic parameters under both steady-state and transient conditions, is the main aim of the article.

2

Thermal dynamics of a building

Matysko R., Dyczkowska M.

Transactions of the Institute of Fluid-Flow Machinery

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2018

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nr 141

31--40

EN

The work presents the thermal dynamics of the building. The mathematical model covers the issues of heat exchange and temperature control in the room due to changing environmental conditions. The presented work describes the operation of the control system due to thermal losses and thermal inertia of the building. Mathematical model introduces a new method of thermal loss analysis in the conditions of variable thermal dynamics of the building.

3

Transient model of heat pump cycle

Matysko R.

Journal of Mechanical and Energy Engineering

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2018

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Vol. 2, No 2

139--146

EN

This paper introduce a transient model of the propane heat pump cycle. The heat pump cycle model includes: a compressor model, a condenser model in lumped parameters, an evaporator model in lumped parameters, an expansion valve model, a heat source model (cooling chamber), a PID control system for heat recovery from superheated refrigerant vapour. The model allows estimate inertia of the heat pump cycle with the system of the heat recovery from superheated propane vapor. The presented theoretical model can determine unsteady and steady state conditions of the different subsystems in the heat pump cycle (condenser, evaporator, compressor). The article presents the results of calculations and determines the time of reaching steady states of the key systems of the heat pump system. The article also presents (in a graphical form) the behavior of the system where the setting was changed after reaching the steady state after 2000s from 50kW to 40kW at the thermal load of the additional heat recovery exchanger.

4

Modifying the Transient Overvoltages in Mixed Power Networks by Inserting Cable Sections

Saied M. M.

Electrical Power Quality and Utilisation. Journal

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2015

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Vol. 18, iss. 1

7--14

EN

The paper deals with the analysis of the electromagnetic transients in mixed power net-works. Special emphasis is made on assessing the effectiveness of using cable sections in reducing the transients in the power network components such as transformer substations. A distributed parameter modeling of the overhead lines, underground cables and transformer windings is applied in the Laplace domain. The simulation can handle the different time waveforms of the sources initiating the transients, the lengths of the cable sections as well as the transformers’ neutral treatment. The direct analytical s-domain solution is numerically inverted in order to get the corresponding time domain results. The affecting parameters such as the line and cable surge impedances, the length of the cable section (or its time delay) and the transformer data, are investigated. A case involving multiple-pulse lightning surges is also addressed. The results of four case studies of known solutions are presented in order to validate the developed mathematical model and computer program.

5

Changes of the thermodynamic parameters in failure conditions of the micro-CHP cycle

Matysko R., Mikielewicz J., Ihnatowicz E.

Archives of Thermodynamics

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2014

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Vol. 35, no. 1

43--59

EN

The paper presents the calculations for the failure conditions of the ORC (organic Rankine cycle) cycle in the electrical power system. It analyses the possible reasons of breakdown, such as the electrical power loss or the automatic safety valve failure. The micro-CHP (combined heat and power) system should have maintenance-free configuration, which means that the user does not have to be acquainted with all the details of the ORC system operation. However, the system should always be equipped with the safety control systems allowing for the immediate turn off of the ORC cycle in case of any failure. In case of emergency, the control system should take over the safety tasks and protect the micro-CHP system from damaging. Although, the control systems are able to respond quickly to the CHP system equipped with the inertial systems, the negative effects of failure are unavoidable and always remain for some time. Moreover, the paper presents the results of calculations determining the inertia for the micro-CHP system of the circulating ORC pump, heat removal pump (cooling condenser) and the heat supply pump in failure conditions.

6

An improved model of a three phase induction motor incorporating the parameter variations

Dey A., Tripathi A., Singh B., Dwivedi B., Chandra D.

Electrical Power Quality and Utilisation. Journal

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2008

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Vol. 14, iss. 1

73--78

EN

A great deal of work is being done on the betterment of control through simulation of the electric drives used for various high-power purposes. The authenticity of the simulated results is based on the accurate modeling of the various parts of the electric drive system. Three–phase Induction motors form an extremely important part of the modern day electric drive system and their usage is continuously on a rise owing to their inherent properties of ruggedness, minimum maintenance requirements and continually increasing efficiencies. Usually the three-phase Induction motor model used in various research works does not incorporate stator and rotor core losses, stator and rotor stray load losses and magnetizing saturation and rotor conductor skin effects. The present paper aims at developing a threephase Induction motor model taking the above losses and effects into account. The dynamic linking of the model to a thermal model considering the temperature dependent resistive elements is an added feature. The motor model described in this paper is the extension of the conventional 2-phase lumped-parameter induction motor model. The biggest advantage is that the model is user-programmable in MA TLAB environment and can be used for system level transient studies. The simulation results of the developed model, with various parameter variations taken into account and subjected to sudden changes in load, show better torque and speed performances of the motor both in steady state and dynamic conditions.