Problems of the starting and operating of hydraulic units and systems in low ambient temperature (Part I)

Problems of the starting and operating of hydraulic units and systems in low ambient temperature (Part I) Severe winters and sweltering summers which more and more often occur nowadays are the reason why machinery designers face many difficulties when designing devices which will be serviceable in extreme ambient conditions. Hence, defining the principles and conditions of safe operation of hydraulically driven machines and devices is essential for their designers and operators. For this reasons the author did a series of tests of hydraulic component and systems in thermal shock conditions (cooled-down component were supplied with hot working medium). In such conditions, starting parameters of the selected hydraulic component and systems which secured safety of their operation were determined. The experimental tests were carried out in the laboratory of the Chair of Hydraulics and Pneumatics, Gdańsk University of Technology.

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Problems of the Starting and Operating of Hydraulic Components and Systems in Low Ambient Temperature (Part IV)

Polish Maritime Research ◽

10.1515/pomr-2017-0089 ◽

2017 ◽

Vol 24 (3) ◽

pp. 45-57 ◽

Cited By ~ 6

Author(s):

Ryszard Jasiński

Keyword(s):

Computer Simulation ◽

Numerical Calculation ◽

Ambient Temperature ◽

Thermal Shock ◽

Simulation Method ◽

Operational Conditions ◽

Working Medium ◽

Numerical Calculation Method ◽

Spool Valve ◽

Low Ambient Temperature

Abstract Designers of hydraulically driven machines and devices are obliged to ensure during design process their high service life with taking into account their operational conditions. Some of the machines may be started in low ambient temperature and even in thermal shock conditions (due to delivering hot working medium to cold components). In order to put such devices into operation appropriate investigations, including experimental ones - usually very expensive and time-consuming, are carried out. For this reason numerical calculations can be used to determine serviceability of a hydraulic component or system operating in thermal shock conditions. Application of numerical calculation methods is much less expensive in comparison to experimental ones. This paper presents a numerical calculation method which makes it possible to solve issues of heat exchange in elements of investigated hydraulic components by using finite elements method. For performing the simulations the following data are necessary: ambient temperature, oil temperature, heat transfer coefficient between oil and surfaces of elements, as well as areas of surfaces being in contact with oil. By means of computer simulation method values of clearance between cooperating elements as well as ranges of parameters of correct and incorrect operation of hydraulic components have been determined. In this paper results of computer simulation of some experimentally tested hydraulic components such as axial piston pump and proportional spool valve, are presented. The computer simulation results were compared with the experimental ones and high conformity was obtained.

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Analysis of the Heating Process of Hydraulic Motors during Start-Up in Thermal Shock Conditions

Energies ◽

10.3390/en15010055 ◽

2021 ◽

Vol 15 (1) ◽

pp. 55

Author(s):

Ryszard Jasiński

Keyword(s):

Pressure Drop ◽

Thermal Shock ◽

Hydraulic Drive ◽

Experimental Tests ◽

Temperature Fields ◽

Heating Process ◽

Ambient Temperatures ◽

Start Up ◽

Working Medium ◽

Hydraulic Motors

Conditions that prevail during harsh winters and hot summers pose a serious challenge for machine designers building devices suitable for operation in extreme weather. It is essential for the designers and the users to define the principles and conditions for the safe operation of machines and devices with hydraulic drive in low ambient temperatures. Bearing in mind the above, the author tested the hydraulic motors in thermal shock conditions (cold motors were fed with a hot working medium). This enterprise required the design and construction of a specialized stand for testing hydraulic motors, including satellite motors, in thermal shock conditions. The stand was equipped with the apparatus and a system for measuring the temperature of the moving parts of the satellite motor. The experimental tests were conducted in the laboratory of the Faculty of Mechanical Engineering and Ship Technology at Gdańsk University of Technology. The paper presents the results of tests of a correctly and incorrectly operating satellite motor during start-up in thermal shock conditions. The results concerned the course of oil temperatures, temperatures of heated elements, oil pressures, and the pressure drop in the motor. The influence of the oil pressure drop in the motor on its temperature increase was determined. The distributions of the temperature fields of the heated elements of the satellite motor during start-up in thermal shock conditions were derived by means of computer simulation. The utilization of the distribution of the temperature fields of the motor elements enables the evaluation and analysis of the work of this unit. The conducted tests may determine the conditions for the proper operation of hydraulic motors started in thermal shock conditions.

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Problems of the Starting and Operating of Hydraulic Components and Systems in Low Ambient Temperature (Part V)

Polish Maritime Research ◽

10.1515/pomr-2017-0135 ◽

2017 ◽

Vol 24 (4) ◽

pp. 47-56 ◽

Cited By ~ 4

Author(s):

Ryszard Jasiński

Keyword(s):

Ambient Temperature ◽

Thermal Shock ◽

Temperature Difference ◽

Hydraulic Drive ◽

Hydraulic Motor ◽

Ambient Temperatures ◽

Start Up ◽

Hydraulic Devices ◽

Low Ambient Temperature

Abstract A large number of hydraulic devices and systems are started in low ambient temperatures. A good example of such a device is the hoisting winch on the ship. Starting hydraulic drive units in thermal shock conditions (rapid supply of hot oil to the cold unit) may lead to incorrect operation of the actuating system, for instance, due to the loss of clearance between cooperating elements. The article presents methods to prevent the disappearance of effective clearance in a hydraulic motor started in thermal shock conditions. For this reason, the structure of the hydraulic satellite motor was complemented by elements creating special channels through which hot oil could flow and additionally heat fixed parts of the motor. This solution ensures faster heating of motor housing, thus decreasing the temperature difference between the housing and the satellites during motor start-up in thermal shock conditions.

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Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽

10.3390/polym13142286 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2286

Author(s):

Jan Kominek ◽

Martin Zachar ◽

Michal Guzej ◽

Erik Bartuli ◽

Petr Kotrbacek

Keyword(s):

Heat Transfer ◽

Ambient Temperature ◽

Convective Heat ◽

Heat Dissipation ◽

High Surface ◽

Heat Sinks ◽

Fourth Power ◽

Molding Process ◽

Ambient Temperatures ◽

University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

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Effect of dietary orange peel extract on physiological, biochemical, and metabolic responses of Japanese quail reared under low ambient temperature

TURKISH JOURNAL OF VETERINARY AND ANIMAL SCIENCES ◽

10.3906/vet-1504-11 ◽

2016 ◽

Vol 40 ◽

pp. 288-297 ◽

Cited By ~ 6

Author(s):

Mehmet ÇİFTÇİ ◽

Ülkü Gülcihan ŞİMŞEK ◽

Bestami DALKILIÇ ◽

Mehmet Ali AZMAN ◽

Ökkeş YILMAZ ◽

...

Keyword(s):

Ambient Temperature ◽

Japanese Quail ◽

Orange Peel ◽

Metabolic Responses ◽

Orange Peel Extract ◽

Peel Extract ◽

Low Ambient Temperature

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The Effect of Process Parameters in Helical Rolling of Balls on the Quality of Products and the Forming Process

Materials ◽

10.3390/ma11112125 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2125 ◽

Cited By ~ 4

Author(s):

Janusz Tomczak ◽

Zbigniew Pater ◽

Tomasz Bulzak

Keyword(s):

Metal Flow ◽

Experimental Tests ◽

Rolling Process ◽

Helical Rolling ◽

Forming Process ◽

University Of Technology ◽

Quality Of Products ◽

Skew Rolling

This paper presents selected numerical and experimental results of a skew rolling process for producing balls using helical tools. The study investigates the effect of the billet’s initial temperature on the quality of produced balls and the rolling process itself. In addition, the effect of billet diameter on the quality of produced balls is investigated. Experimental tests were performed using a helical rolling mill available at the Lublin University of Technology. The experiments consisted of rolling 40 mm diameter balls with the use of two helical tools. To determine optimal rolling parameters ensuring the highest quality of produced balls, numerical modelling was performed using the finite element method in the Forge software. The numerical analysis involved the determination of metal flow kinematics, temperature and damage criterion distributions, as well as the measurement of variations in the force parameters. The results demonstrate that the highest quality balls are produced from billet preheated to approximately 1000 °C.

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Mechanical-Level Hardware-In-The-Loop and Simulation in Validation Testing of Prototype Tower Crane Drives

Energies ◽

10.3390/en13215727 ◽

2020 ◽

Vol 13 (21) ◽

pp. 5727

Author(s):

Michał Michna ◽

Filip Kutt ◽

Łukasz Sienkiewicz ◽

Roland Ryndzionek ◽

Grzegorz Kostro ◽

...

Keyword(s):

Laboratory Testing ◽

Environmental Parameters ◽

Experimental Tests ◽

Drive System ◽

Hardware In The Loop ◽

Dynamic Simulations ◽

Tower Crane ◽

University Of Technology ◽

New Type ◽

Drive Systems

In this paper, the static and dynamic simulations, and mechanical-level Hardware-In-the-Loop (MHIL) laboratory testing methodology of prototype drive systems with energy-saving permanent-magnet electric motors, intended for use in modern construction cranes is proposed and described. This research was aimed at designing and constructing a new type of tower crane by Krupiński Cranes Company. The described research stage was necessary for validation of the selection of the drive system elements and confirmation of its compliance with applicable standards. The mechanical construction of the crane was not completed and unavailable at the time of testing. A verification of drive system parameters had to be performed in MHIL laboratory testing, in which it would be possible to simulate torque acting on the motor shaft. It was shown that the HIL simulation for a crane may be accurate and an effective approach in the development phase. The experimental tests of selected operating cycles of prototype crane drives were carried out. Experimental research was performed in the LINTE^2 laboratory of the Gdańsk University of Technology (Poland), where the MHIL simulator was developed. The most important component of the system was the dynamometer and its control system. Specialized software to control the dynamometer and to emulate the load subjected to the crane was developed. A series of tests related to electric motor environmental parameters was carried out.

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