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

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

Polish Maritime Research ◽

10.2478/v10012-007-0095-9 ◽

2008 ◽

Vol 15 (4) ◽

pp. 37-44 ◽

Cited By ~ 3

Author(s):

Ryszard Jasiński

Keyword(s):

Ambient Temperature ◽

Thermal Shock ◽

Experimental Tests ◽

Hot Working ◽

Ambient Conditions ◽

Safe Operation ◽

University Of Technology ◽

Working Medium ◽

Low Ambient Temperature

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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Simulation Analysis of Static Characteristics of CJX2-40 Type AC Contactor Electromagnetic Mechanism

The Open Electrical & Electronic Engineering Journal ◽

10.2174/1874129001408010467 ◽

2014 ◽

Vol 8 (1) ◽

pp. 467-473

Author(s):

Jiaxian Li

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Numerical Calculation ◽

Boundary Value Problems ◽

Simulation Analysis ◽

Boundary Value ◽

Simulation Method ◽

Limited Range ◽

Numerical Calculation Method ◽

Element Method

At present, the finite element method has been widely used in electrical engineering; value has an absolute advantage in the field of solving the problem of position in the electromagnetic boundary. From the perspective of historical development, for solving the electromagnetic boundary value problems, four kinds of methods are used namely; graphical method, simulation method, analytical method and numerical calculation . This study introduced finite element method which has developed rapidly. Before finite element method, numerical calculation method was used, although this method was effective to a certain extent but the results showed that it had a limited range of the electromagnetic boundary value problems to be solved.

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Influence of Design of Hydraulic Components on their Operation in Low Ambient Temperatures

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.490.106 ◽

2011 ◽

Vol 490 ◽

pp. 106-118 ◽

Cited By ~ 2

Author(s):

Ryszard Jasiński

Keyword(s):

Computer Simulation ◽

Thermal Shock ◽

Thermal State ◽

Weather Conditions ◽

Simulation Method ◽

Large Temperature ◽

Shock Condition ◽

Warm Up ◽

Ambient Temperatures ◽

Start Up

In many machines and devices there are hydraulic drives. They should operate well in various weather conditions, also in low ambient temperatures. Some malfunctions may occur during operation of hydraulic system in a so called “thermal shock condition”, which happens when frozen hydraulic component (e.g. hydraulic pump, motor or directional spool valve) is suddenly supplied with hot oil. Transient thermal state emerges in these conditions. Particular elements of component warm up differently. This results in different thermal expansion of components during warm up, which is changing the size of clearance between cooperating elements. Experimental tests of hydraulic components in low ambient temperatures were conducted in the hydraulic laboratory of the Faculty of Mechanical Engineering of Gdansk University of Technology. They concerned: orbital motors, satellite motors, gear pumps, spool valves (also proportional), piston pumps, and hydraulic cylinders. It was proved, that in thermal shock conditions some malfunctions may occur, especially with large temperature differences between oil and component. Based on results of the tests of hydraulic components and systems start-up in low ambient temperatures, one can perform a change in components design, change the type of material of components elements, and even prepare a proper procedure to be followed during start-up of cold hydraulic components and systems. In the article discusses some designs of hydraulic components resistant to thermal shock, and how to prepare components to work in low temperatures, e.g. by providing system with an additional heater to ensure uniform heating of elements in components. Change in design of hydraulic components resistant to thermal shock conditions can be obtained through computer simulation method. Analytic and computer simulation methods can be used by engineers who design machines and devices that work in low ambient temperatures.

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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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Submerged upflow biotower operation and computer simulation

Water Science & Technology ◽

10.2166/wst.1994.0554 ◽

1994 ◽

Vol 30 (11) ◽

pp. 143-146

Author(s):

Ronald D. Neufeld ◽

Christopher A. Badali ◽

Dennis Powers ◽

Christopher Carson

Keyword(s):

Computer Simulation ◽

Benzoic Acid ◽

Computer Model ◽

Rate Constants ◽

Batch Mode ◽

Operational Conditions ◽

First Order ◽

Low Concentrations ◽

Biological Transformation ◽

Kinetics Of

A two step operation is proposed for the biodegradation of low concentrations (< 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.

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