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.

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 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.

Entropy Generation Minimization of Confined Nanofluids Laminar Flow Around a Block

2010 ◽  
Author(s):  
Mehdi Boghrati ◽  
Ehsan Ebrahimnia Bajestan ◽  
Vahid Etminan
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Entropy Generation ◽  
Control Volume ◽  
Spherical Shape ◽  
Temperature Fields ◽  
Heating Process ◽  
Water Mixture ◽  
Entropy Generation Minimization

According to the importance of cooling and heating process of a solid object, entropy generation in confined flow around a block is studied. In the current study, numerical simulation of laminar flow and heat transfer of nanofluids with nanoparticles of different shapes is considered. The nanofluids are water mixture with either Al2O3 nanoshperes or carbon nanotubes (CNTs). The incompressible Navier-Stokes and energy equations are solved numerically in a body fitted coordinates system using a control volume technique. The flow patterns and temperature fields for different values of the particles concentrations are examined in detail. Furthermore, the effects of nanoparticles shape and concentration on the heat transfer are studied. Furthermore the influences of nanofluids on pressure drop and pump power is examined. On the other hand, the entropy generation minimization is considered as the optimization criterion. The results indicate that in most cases the nanofluids enhance the heat transfer as well as pressure drop. It is interesting to note that the shape of nanoparticles is critical in determining the key mechanism of heat transport in nanofluids. Nanofluids with cylindrical nanoparticles exhibit a greater increase in heat transfer compared with nanofluids having spherical shape nanoparticles.

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

2008 ◽  
Vol 15 (4) ◽  
pp. 37-44 ◽  
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.

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.

scholarly journals Development of a Method for Monitoring the Process of Heating the Lining of High-Temperature Units

2020 ◽  
pp. 462-472
Author(s):  
Evgeniy V. Prikhodko
Keyword(s):  
High Temperature ◽  
Physical Model ◽  
Thermal State ◽  
Emergency Situation ◽  
Temperature Fields ◽  
Heating Process ◽  
Thermal Processes ◽  
Nonstationary Heat Conduction ◽  
Thermal Unit ◽  
Working Medium

This article proposes a new method for monitoring the thermal state of the lining of hightemperature units. Firstly, it is shown that the main methods for monitoring the thermal state of the lining are limited to obtaining data to prevent an emergency situation – leakage of the working medium through the lining and does not allow to obtain data on the temperature distribution over the cross section of the lining, for monitoring nonstationary thermal processes. Secondly, a method for determining the thermal state of the lining of a thermal unit is proposed, which allows one to obtain data on the temperature fields of the lining in the process of nonstationary heat conduction and use these values to control the process. Thirdly, to test the developed method, a physical model of the process of heating the lining of a high-temperature unit was created. Fourth, testing the physical model of the heating process showed that the developed method can be applied in practice, since its error does not exceed 10%

Study on the Flow Characteristics of Shengli Oilfield Super Heavy Oil

2017 ◽  
Vol 10 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Wang Shou-long ◽  
Li Ai-fen ◽  
Peng Rui-gang ◽  
Yu Miao ◽  
Fu Shuai-shi
Keyword(s):  
Pressure Drop ◽  
Pressure Gradient ◽  
Heavy Oil ◽  
Flow Characteristics ◽  
Fluid Viscosity ◽  
Linear Flow ◽  
Start Up ◽  
Non Linear ◽  
Core Permeability ◽  
Velocity Pressure

Objective:The rheological properties of oil severely affect the determination of percolation theory, development program, production technology and oil-gathering and transferring process, especially for super heavy oil reservoirs. This paper illustrated the basic seepage morphology of super heavy oil in micro pores based on its rheological characteristics.Methods:The non-linear flow law and start-up pressure gradient of super heavy oil under irreducible water saturation at different temperatures were performed with different permeable sand packs. Meanwhile, the empirical formulas between start-up pressure gradient, the parameters describing the velocity-pressure drop curve and the ratio of gas permeability of a core to fluid viscosity were established.Results:The results demonstrate that temperature and core permeability have significant effect on the non-linear flow characteristics of super heavy oil. The relationship between start-up pressure gradient of oil, the parameters representing the velocity-pressure drop curve and the ratio of core permeability to fluid viscosity could be described as a power function.Conclusion:Above all, the quantitative description of the seepage law of super heavy oil reservoir was proposed in this paper, and finally the empirical diagram for determining the minimum and maximum start-up pressure of heavy oil with different viscosity in different permeable formations was obtained.

Flow Coefficient Evaluation of Poppet Valves Used in Reciprocating Compressors for LDPE

2008 ◽  
Author(s):  
Enzo Giacomelli ◽  
Massimo Schiavone ◽  
Fabio Manfrone ◽  
Andrea Raggi
Keyword(s):  
Pressure Drop ◽  
Time Pressure ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Operating Life ◽  
High Fatigue ◽  
Strongly Connected ◽  
And Performance ◽  
Poppet Valves

Poppet valves have been used for a long time for very high pressure reciprocating compressors, as for example in the case of Low Density Polyethylene. These applications are very critical because the final pressure can reach 350 MPa and the evaluation of the performance of the machines is strongly connected to the proper operation and performance of the valve itself. The arrangement of cylinders requires generally a certain compactness of valve to withstand high fatigue stresses, but at the same time pressure drop and operating life are very important. In recent years the reliability of the machines has been improving over and over and the customers’ needs are very stringent. Therefore the use of poppet valves has been extended to other cases. In general the mentioned applications are heavy duty services and the simulation of the valves require some coefficients to be used in the differential equations, able to describe the movement of plate/disk or poppet and the flow and related pressure drop through the valves. Such coefficients are often determined in an experimental way in order to have a simulation closer to the real operating conditions. For the flow coefficients it is also possible today to use theoretical programs capable of determining the needed values in a quick and economical way. Some investigations have been carried out to determine the values for certain geometries of poppet valves. The results of the theory have been compared with some experimental tests. The good agreement between the various methods indicates the most suitable procedure to be applied in order to have reliable data. The advantage is evident as the time necessary for the theoretical procedure is faster and less expensive. This is of significant importance at the time of the design and also in case of a need to provide timely technical support for the operating behavior of the valves. Particularly for LDPE, the optimization of all the parameters is strongly necessary. The fatigue stresses of cylinder heads and valve bodies have to match in fact with gas passage turbulence and pressure drop, added to the mechanical behavior of the poppet valve components.

scholarly journals Influence of Residual Fuel Sediment on Stress-Strain State of a Vertical Steel Tank

2021 ◽  
Vol 134 (3) ◽  
pp. 60-64
Author(s):  
R. R. Sultanbekov ◽  
◽  
A. M. Schipachev ◽  
I. S. Leonov ◽  
◽  
...  
Keyword(s):  
Strain State ◽  
Branch Pipe ◽  
Oil Products ◽  
Temperature Fields ◽  
Stress Strain ◽  
Ambient Temperatures ◽  
Stress Strain State ◽  
Steel Tank ◽  
Total Sediment ◽  
Maximum Stresses

The article studies the formation of the total sediment by the incompatibility of residual fuels and oil products, analyzes and calculates the stress-strain state of the tank taking into account oil products and sediment. The studies examined the influence of temperature fields on the sedimentation of a mixture of residual fuels caused by the incompatibility of these components. Temperatures of a stored product, namely residual fuel RMK-700, and ambient temperatures are taken into account when modelling in ANSYS product. Effects that oil product has separately and oil product with bottom sediments have on a stress-stain state are compared. Laboratory tests were performed to accurately measure density depending on various temperatures. By means of finite element method a stress-stain state of a vertical steel tank RVS-20000 is examined, the calculations showed that the maximum stresses are located in zones of the weld seam and in the places of installation of the receiving-distributing branch pipe and manhole. In these areas bottom sediment and temperature difference influence the stress-stain state greatly, with the stresses becoming even higher as the wall gets thinner.

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