Volume 3, Number 1 (2017)
Investigations on the Innovation Model of Exergy Effectiveness of Air Conditioning System for Operating Cleanrooms
Dmytro Harasym, Volodymyr Labay
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: March 12, 2017. Revised: April 06, 2017. Accepted: April 14, 2017
© 2017, The Authors. Published by Lviv Polytechnic National University
Abstract
The issue of fuel and energy saving is a top priority for energy technological systems (ETS) such as air conditioning systems (ACS). Thus, reduction of energy consumption for ACS requires optimization of these systems which can be obtained on the basis of the exergy analysis. This analysis takes into account not only the quantity of the energy being consumed but also its quality. By taking into account the exergy during calculation of balances and various characteristics of ETC (including ACS) the scientific and engineering problems can be solved in a simple and easily understandable way. Frequent mistakes caused by ignoring the quality of transformations can be avoided. Innovation mathematical research model of the existing central straight flow air conditioning system for operating cleanrooms with the aim of computer estimation of its energy effectiveness by virtue of exergetic output-input ratio depending on different factors, which have influence on its operation, is presented in this article. The dependence of exergetic output-input ratio ηe of the existing air conditioning system on temperature difference between the inside and the supplied air ∆tS = tin – tS was defined based on this model.
Keywords: exergy balance; air conditioning systems; cleanrooms; exergy efficiency.
Література – 20.
Efficiency of Modern Wind Turbines in Real Conditions
Kostiantyn Pokrovskyi, Olgerd Mavrin, Andriy Muzychak
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: March 03, 2017. Revised: April 25, 2017. Accepted: May 02, 2017
© 2017, The Authors. Published by Lviv Polytechnic National University
Abstract
One of the problems of wind energy is determined insufficient information available about the effectiveness of wind farms in the real life conditions, due in particular to commercial issues of use. On the one hand it is associated with the wind loads in effective areas, on the other – lasting licensed wind parameters measurement with difficult access conditions. The paper estimates the economic efficiency of wind farm generators of different capacities. It is shown that in this way we can calculate the wind power parameters necessary for the preliminary analysis of the economic efficiency of – annual electricity production, profitability and return on investment. As a result, the estimation of costs for wind turbines and their installation and operation, profit margins and payback period were estimated. The high efficiency of wind power in terms of the Carpathian region of Ukraine provided detailed characteristics of wind turbine choice for real parameters of wind loads has been shown.
Keywords: wind turbine; wind station; efficiency; productivity.
Література – 9.
Digital Complex for Modeling Processes in Electric Circuits
with Protection and Automatic Devices
Oleksandr Ravlyk, Nazar Ravlyk
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: February 13, 2017. Revised: March 13, 2017. Accepted: March 21, 2017.
© 2017, The Authors. Published by Lviv Polytechnic National University
Abstract
The developed digital complex for modeling electromechanical and electromagnetic processes in electric circuits of any configuration with electromagnetic devices, control devices, synchronous and asynchronous motors including their control systems, protection devices and automation, allows us to carry out computation ranging from arc and voltage restoration of switches, to process of starting and restarting of electric motors. Digital Complex is designed for personal computers and computer systems in a Windows environment. Decision modeling tasks were performed by means of design schemes and their parameters created in a graphical environment. To form the majority of schemes of electro technical devices and protection systems a basic set of graphic elements, as well as unilateral and reciprocal links between them is provided. In addition to mutual inductances, models of the controlled dynamic and static connections by management functions developed for modeling electrical machines were used. The authors have developed the new effective methods for forming and solving equations for the significant performance and modeling in real time. The proposed complex is intended for engineering and scientific researches, and can be used for the formation of training systems for students and staff of the electric enterprises.
Keywords: digital complex; electromechanical and electromagnetic processes; modeling in real time; nonlinear model of the transformer; nonlinear model of the electric motor.
Література – 9.
Preparation of Papers for the Journal EECS
Research and Analysis of Rapidly Changing Gas Flow Temperatures Measurement Methods
Vasyl Fedynets, Leonid Lesovoi, Bohdan Chaban
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: April 27, 2017. Revised: May 26, 2017. Accepted: June 02, 2017
© 2017, The Authors. Published by Lviv Polytechnic National University
Abstract
The temperature of a transducer sensitive element, as a result of its heat capacity, will always lag behind the temperature of the gas flow if this temperature changes. When measuring the flow temperature that varies in time, the transducer doesn’t follow the changes in temperature immediately because its sensitive element temperature changes after some time. The distortions of the transducer readings are caused by the thermal inertia due to non-stationary heat processes in the transducers, as well as between transducer and the environment. Since complete elimination of real temperature transducer inertia is not possible, the transducers with some finite values of the thermal inertia are used at practice to measure the varying gas flow temperature. The necessary information about the flow temperature can be obtained by analyzing the record of the non-stationary measurement process. In this case a direct calculation of the flow temperature is made or a correction of the temperature transducer readings delay is made. The results of research and analysis of measurement methods of rapidly changing gas flow temperatures by the direct calculation of the flow temperature and by correcting the temperature transducer readings are presented in this paper.
Keywords: gas flow; measurement; heat exchange; temperature; temperature transducer.
Література – 9.
Methods for Defining the Binary Coal Mixture Composition
in the Pulverized Coal-Fired Boiler
Yevhen Pistun, Stepan Mysak, Halyna Matiko
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: February 14, 2017. Revised: March 16, 2017. Accepted: March 22, 2017
© 2017, The Authors. Published by Lviv Polytechnic National University
Abstract
The paper deals with the methods for defining the composition of the coal mixture burnt in boilers at combined heat and power plants. Indirect methods for defining the proportions of the two grades of coal in the mixture based on the available information on the quality characteristics of the coal are proposed. According to the first method the coal mixture composition is determined based on the values of volatile substances content in the combustible mass of the coal mixture and of each grade of coal making up the mixture. The second method uses the lower combustion heat of the coal mixture and lower combustion heats of the two grades of coal that the mixture consists of. The uncertainties of the results obtained by the developed methods are evaluated.
Keywords: methods; coal mixture; mixture composition; boiler; pulverized coal system; uncertainty.
Література – 10.
Вимоги до оформлення статей для подання до друку в журнал EECS
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