Experimental Research on Polymer-Based Coaxial Sealing Systems of Hydraulic Cylinders for Small Displacement Velocities

Reducing friction in the coaxial sealing systems of hydraulic cylinders is one of the solutions for increasing the energy efficiency of industrial actuations. This is a requirement, particularly in the case of small velocities that carry the risk of eigen-vibrations and/or stick-slip. The authors discuss the experimental research conducted on three coaxial sealing systems made from thermoplastic polymer and polyurethane type materials. The paper presents the equipment and method used for the experimental determination of static and kinematic friction coefficients and discusses the subsequent results obtained to test different working parameters. The experimentally determined friction coefficients yielded a range of materials recommended for coaxial seals such as to minimize the occurrence of jerky operation.

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Energy efficiency of different bus subsystems in Belgrade public transport

Thermal Science ◽

10.2298/tsci151116193m ◽

2015 ◽

Vol 19 (6) ◽

pp. 2233-2244

Author(s):

Slobodan Misanovic ◽

Zlatomir Zivanovic ◽

Slaven Tica

Keyword(s):

Energy Efficiency ◽

Simulation Model ◽

Experimental Determination ◽

Public Transport ◽

Drive System ◽

Theoretical Simulation ◽

Driving Cycles ◽

Electric Bus

Research in this paper comprised experimental determination of energy efficiency of different bus subsystems (diesel bus, trolleybus and fully electric bus) on chosen public transport route in Belgrade. Experimental measuring of energy efficiency of each bus type has been done based on the analysis of parameters of vehicle driving cycles between stops. Results of this analysis were basis for development of theoretical simulation model of energy efficiency. The model was latter compared with the results of simulation done by "Solaris bus & Coach" company for the chosen electric bus route. Based on demonstrated simulation, characteristics of electric bus batteries were defined, the method and dynamic of their recharge was suggested, as well as choice for other aggregates for drive system and technical characteristics for the electric buses were suggested.

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Analysis of energy efficiency of air handling unit with integrated air to air heat exchanger in heating mode

E3S Web of Conferences ◽

10.1051/e3sconf/202020701002 ◽

2020 ◽

Vol 207 ◽

pp. 01002

Author(s):

Slav Valchev ◽

Ivan Mihaylov

Keyword(s):

Energy Efficiency ◽

Heat Exchanger ◽

Experimental Determination ◽

Mass Flow ◽

Coefficient Of Performance ◽

Supply Side ◽

High Effectiveness ◽

Air Handling Unit ◽

Heating Mode

Object of the present study is an experimental determination of energy efficiency parameters of air handling unit with integrated air to air heat exchanger: effectiveness of air to air heat exchanger, coefficient of performance and specific fan power of air handling unit. A daily performance of air handling unit is conducted. Effectiveness of supply side of air to air heat exchanger in range of 42.4 % to 52.5 % is received. Coefficient of performance in range of 1.50 to 2.08 and specific fan power of air handling unit in range of 1.39 kW/(m3/s) to 2.08 kW/(m3/s) are received. It was found experimentally that effectiveness of air to air heat exchanger depends on values of mass flow of supply and the exhaust air. High values of mass flow of the exhaust air responds to high effectiveness of supply side of air to air heat exchanger.

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Residual Stresses Generated by the Combined Burnishing - Cutting Process in the Worked Parts

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.657.103 ◽

2014 ◽

Vol 657 ◽

pp. 103-107 ◽

Cited By ~ 1

Author(s):

Gheorghe Brabie ◽

Gheorghe Mustea ◽

Bogdan Chirita

Keyword(s):

Magnesium Alloy ◽

Residual Stresses ◽

Experimental Determination ◽

Experimental Investigations ◽

Machined Surface ◽

Combined Process ◽

Part Surface ◽

Working Parameters ◽

Compressive Residual Stresses

The cutting followed by burnishing, used like a combined process, leads to the improvement of the part surface quality (roughness, hardness, microstructure etc.) and to reduction of the costs and manufacturing times as a function of different working parameters. One of the factors and parameters that characterize the machined surface by this combined process is the residual stresses that are generated and located in the part deformed strata. The present paper analyses the results concerning the experimental determination of the residual stresses generated in the machined surfaces of parts made from magnesium alloy by the burnishing - turning combined process. The experimental investigations have shown that in the machined strata the combined process determines the occurrence of the compressive residual stresses and hence the fatigue and cracking resistances of the machined materials will be improved.

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EXPRESS ESTIMATION OF THE ENERGY EFFICIENCY OF A CENTRIFUGAL PUMP WITHOUT EXPERIMENTAL DETERMINATION OF ITS EXPENSES

Scientific Bulletin of Ivano-Frankivsk National Technical University of Oil and Gas ◽

10.31471/1993-9965-2019-1(46)-46-52 ◽

2019 ◽

pp. 46-52

Author(s):

V. S. Kostyshyn ◽

P. M. Nykolyn

Keyword(s):

Energy Efficiency ◽

Experimental Determination ◽

Centrifugal Pump ◽

Operating Mode ◽

Total Efficiency ◽

Operating Characteristics ◽

Hydraulic Machines ◽

Calculated Load ◽

Load Angle

Using a mathematical model, created on the basis of the electrohydraulic analogy method, a methodology for express estimation of the energy efficiency of a centrifugal pump was developed. The design load angle for analyzing the efficiency of operating modes of hydraulic machines is determined. The dependence of the power-driven engine shaft and the total efficiency of the centrifugal pump on its calculated load angle is established. The relationship between load angle and speed coefficient, which is a prototype of an electromagnetic load angle which characterizes the synchronous machine operating mode, is determined. It is established the dependence of the main pump head on the calculated load angle and the differential pressure created by the centrifugal pump. The developed methodology makes it possible to avoid significant technical and financial difficulties, since flow meters have a high cost and certain requirements for installation, while manometers are established by the standard requirements of the technological process. The estimated value of the load angle of the centrifugal pump through its catalog parameters is determined. The operating characteristics for the main centrifugal pump of type НМ-7000-210 were calculated and built without experimental determination of its head. Such approach showed a good coincidence of calculated and experimental characteristics. Relative error of energy characteristics does not exceed ten percents. The proposed methodology can be used for express estimation of the efficiency of energy transformations of the whole electric drive pump unit. Express-analysis is a key to successful management of the energy economy through timely detection of inefficient modes of operation of electric-driven pump units and makes energy research cheaper.

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