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

2011 ◽  
Vol 490 ◽  
pp. 106-118 ◽  
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.

Influence of Type of Material on Performance of Hydraulic Components in Thermal Shock Conditions

2011 ◽  
Vol 183 ◽  
pp. 95-100 ◽  
Author(s):  
Ryszard Jasiński
Keyword(s):  
Thermal Shock ◽  
Material Properties ◽  
Hydraulic System ◽  
Correct Operation ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Start Up ◽  
Working Medium ◽  
Machine Safety ◽  
Selection Of

During the start-up of a hydraulic system in low ambient temperatures an incorrect operation may occur. The principles and conditions of safely operating hydraulic driven machines and devices are essential to designers and operators. For this reason the author of this article has conducted a series of tests on hydraulic components and systems in thermal shock conditions (cooled-down components were supplied with hot working medium). In such conditions, the initial parameters of the hydraulic components and systems determine their correct operation. During the start-up of a hydraulic system in thermal shock conditions, elements of hydraulic components warm up in a non-uniform way, due to various material properties and shapes of parts. Differences in clearances between elements and may lead to the faulty performance of hydraulic components and machine break-down. The selection of appropriate materials for various hydraulic component parts should increase machine safety during start-up in thermal shock conditions.

Determination of Ability of Hydrotronic Systems to Start in Low Ambient Temperatures

2010 ◽  
Vol 164 ◽  
pp. 31-36 ◽  
Author(s):  
Ryszard Jasiński
Keyword(s):  
Thermal Shock ◽  
Hydraulic System ◽  
Transfer Coefficients ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Heat Transfer Coefficients ◽  
Electric Control ◽  
Start Up ◽  
Working Medium

During start-up of hydrotronic system (hydraulic system with electric control) in low ambient temperatures a faulty operation may occur. The principles and conditions of safe operation of hydraulically (hydrotronically) driven machines and devices is essential for their designers and operators. For these reasons the author did a series of tests of hydraulic (hydrotronic) components and systems under thermal shock conditions (cooled-down components were supplied with hot working medium). In such conditions starting parameters of the selected hydrotronic components and systems, which secured safety of their operation, were determined. During start-up of a hydrotronic system under thermal shock conditions elements of hydraulic components warm up in a non-uniform way, due to varying material and shape properties. This causes change of clearances between the cooperating elements and may lead to faulty performance of hydraulic components and result in machine break-down. Heat transfer coefficients between oil and swilled element were determined and used for a calculation method developed by the author. The method enables to predict correct or incorrect operation of hydrotronic system.

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

2017 ◽  
Vol 24 (3) ◽  
pp. 45-57 ◽  
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.

scholarly journals Mathematical simulation of thermal state of digital current and voltage transformer in unfavourable weather conditions

2018 ◽  
Vol 194 ◽  
pp. 01021 ◽  
Author(s):  
Elena E. Gotovkina ◽  
Grigory I. Parfenov ◽  
Nikolay N. Smirnov ◽  
Vladimir D. Lebedev ◽  
Vladimir V. Tyutikov
Keyword(s):  
Mathematical Simulation ◽  
Thermal State ◽  
Weather Conditions ◽  
The Finite Element Method ◽  
Voltage Transformer ◽  
Measuring Device ◽  
Ambient Temperatures ◽  
Unfavourable Weather ◽  
Series Of Experiments ◽  
The Impact

This study examines issues relating to heat exchange between an innovative 6(10) kV current and voltage transformer (and its components) and its environment in unfavourable weather conditions. Existing designs of digital current and voltage transformers are featured in systems of commercial and technical electric power accounting, and also relay protection and automation. We have presented the results of mathematical simulation of the thermal state of both a single resistor included in our measuring device, and the digital transformer as a whole. Simulation was performed using the finite element method. We have taken into account the impact of such factors as direct and diffused solar radiation, high ambient temperatures and various voltage levels on the thermal state of the functioning equipment. To verify the developed mathematical model we have presented the results of a series of experiments conducted in a high-voltage environmental chamber. Our study conclusively shows that voltage, insolation and ambient temperature significantly affect the thermal state of a functioning current and voltage transformer.

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

Energies ◽  
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.

Operation and Maintenance Improvements of Steam Turbines Subject to Frequent Start by Rotor Stress Monitoring

2020 ◽  
Author(s):  
Federico Bucciarelli ◽  
Damaso Checcacci ◽  
Gabriele Girezzi ◽  
Annamaria Signorini
Keyword(s):  
Fatigue Damage ◽  
Thermal Stresses ◽  
Low Cycle Fatigue ◽  
Weather Conditions ◽  
Control Panel ◽  
Steam Turbines ◽  
Stress Monitoring ◽  
Warm Up ◽  
Start Up ◽  
Critical Components

Abstract Steam Turbines operating in Concentrated Solar Plants and Peaking Combined Cycles are subjected to daily thermal stresses, induced by start-ups and load variations, deeply affecting allowed production per day. The extent and number of such thermal stresses is largely depending on the capability, of both plant and operators, to smooth the variations in steam temperature and load resulting from both weather conditions (in CSPs) and grid demand. In this operating scenario, conservative simplified rules are normally applied to determine daily warm-up times duration at starts, to preserve critical components from Low Cycle Fatigue damage; the planned maintenance intervals, as well, have been typically defined on the basis of a specified number of starts and running hours. In this article, the application of an online Rotor Stress Monitoring (RSM) technology, installed in the Steam Turbine User Control Panel, is used to directly determine the fatigue damage cumulated by each Start-Up and variation in operating condition. The results of application of this technology, with respect to standard formulations, are shown for a specific Concentrated Solar Plant across an operating period of four years. It is shown how, using the RSM as a basis for either startup or maintenance scheduling, can result in optimization of start-up times and maintenance intervals both for new units and retro-fit. The applicability of rotor stress direct monitoring and life analysis to higher temperature services is also introduced.

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

2017 ◽  
Vol 24 (4) ◽  
pp. 47-56 ◽  
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.

scholarly journals Investigations of the influence of engine thermal state on the fuel consumption of passenger vehicles

2017 ◽  
Vol 169 (2) ◽  
pp. 49-52
Author(s):  
Wojciech ADAMSKI ◽  
Stanisław POLAK
Keyword(s):  
Fuel Consumption ◽  
Thermal State ◽  
Climate Chamber ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Passenger Vehicles ◽  
Wide Range

The paper presents the results of investigations of the fuel consumption of two vehicles performed for non-stabilized engine temperature in the start and warm up phases. The measurements were performed in a wide range of ambient temperatures from –18°C to +25°C. In order to obtain such conditions the tests were carried out in a climate chamber.

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