THE USE OF HYDRAULIC “LONG” LINES IN MODERN SUBSEA PRODUCTION FACILITIES

2020 ◽  
pp. 43-51
Author(s):  
K. A. Trukhanov
Keyword(s):  
Mathematical Model ◽  
Working Fluid ◽  
Hydraulic Systems ◽  
Signal Attenuation ◽  
Friction Resistance ◽  
Distributed Parameters ◽  
Long Line ◽  
Pump Flow Rate ◽  
Modern Application ◽  
Mathematical Relationships

Describes and provides a brief description of the modern application of hydraulic “long” lines in a subsea production facility. The necessity and relevance of developing a mathematical model that allows us to predict and carry out practical calculations of ongoing processes in hydraulic “long” lines, spending the minimum amount of time and resources on this, is shown. In the article are provided general provisions and basic mathematical relationships for performing calculations and modeling unsteady processes in hydraulic lines with distributed parameters. Boundary conditions are given that make it possible to obtain a closed system of equations representing a mathematical model of hydraulic “long” lines. The scientific novelty of the results presented in the article is that the main criteria necessary for the design and operation of equipment containing hydraulic “long” lines were obtained and presented. Among which it is especially necessary to note, dependences for the unsteady coefficient of hydraulic friction resistance of the pipe λ. Criteria are also given for determining the amplitude of signal attenuation in the case of using a hydraulic “long” line as a line for transmitting information, as well as a criterion that allows to determine the minimum pump flow rate to ensure a given level of purity of the working fluid during operation and maintenance of equipment with hydraulic “long” lines, which It is especially important and relevant in practice for the selection of equipment and determine the minimum required power. The content of the article is interest to specialists involved in the development of hydraulic systems with hydraulic “long” lines.

scholarly journals PRINCIPLES OF CONSTRUCTION OF THE GENERALIZED MATHEMATICAL MODEL OF THE HYDRAULIC EXTINGUISHER OF OSCILLATIONS OF THE PASSENGER CAR

2021 ◽  
Vol 1 (38) ◽  
pp. 173-184
Author(s):  
I. Shcherbyna
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Working Fluid ◽  
Operating Parameters ◽  
Hydraulic Systems ◽  
Passenger Cars ◽  
Passenger Car ◽  
Periodic Movement ◽  
Depth Analysis ◽  
The Impact

The study of the processes associated with the use of working fluids in the elements of hydraulic drives was preceded by studies of the unsteady periodic movement of the working fluid in the pipelines of hydraulic systems. Such processes take place in hydraulic drives and their elements, and are associated with the compressibility of the working fluid. The stability of the operation of hydraulic valves, which are supplied to hydraulic systems in order to maintain, within the required limits, pressures or flow rates, is also largely predetermined by non-stationary hydro mechanical processes occurring in the pipelines of these systems, channels and chambers of hydraulic devices. The peculiarities of the working processes of passive vibration dampers of passenger cars include the interaction of the working fluid with moving parts and its flow through the channels and through the calibrated holes with local artificial resistance. For in-depth analysis of changes in operating parameters, it is necessary to use a mathematical model that should reflect the processes that occur during the operation of the hydraulic device. In the presented article the generalized mathematical model of the hydraulic damper of fluctuations of the passenger car of the НЦ-1100 type is developed. This model takes into account the special operating conditions of the hydraulic shock absorber, which allows you to study the impact of operating parameters on the performance of the device.

A Numerical Study of Unsteady Natural Convection in a Rectangular Enclosure: The Effect of Compressibility

2004 ◽  
Author(s):  
K. M. Akyuzlu ◽  
Y. Pavri ◽  
A. Antoniou
Keyword(s):  
Mathematical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Vertical Wall ◽  
Ideal Gas ◽  
Working Fluid ◽  
Two Dimensional ◽  
Algebraic Equations ◽  
Rectangular Enclosure ◽  
Circulation Patterns

A two-dimensional, mathematical model is adopted to investigate the development of buoyancy driven circulation patterns and temperature contours inside a rectangular enclosure filled with a compressible fluid (Pr=1.0). One of the vertical walls of the enclosure is kept at a higher temperature then the opposing vertical wall. The top and the bottom of the enclosure are assumed insulated. The physics based mathematical model for this problem consists of conservation of mass, momentum (two-dimensional Navier-Stokes equations) and energy equations for the enclosed fluid subjected to appropriate boundary conditions. The working fluid is assumed to be compressible through a simple ideal gas relation. The governing equations are discretized using second order accurate central differencing for spatial derivatives and first order forward finite differencing for time derivatives where the computation domain is represented by a uniform orthogonal mesh. The resulting nonlinear equations are then linearized using Newton’s linearization method. The set of algebraic equations that result from this process are then put into a matrix form and solved using a Coupled Modified Strongly Implicit Procedure (CMSIP) for the unknowns (primitive variables) of the problem. A numerical experiment is carried out for a benchmark case (driven cavity flow) to verify the accuracy of the proposed solution procedure. Numerical experiments are then carried out using the proposed compressible flow model to simulate the development of the buoyancy driven circulation patterns for Rayleigh numbers between 103 and 105. Finally, an attempt is made to determine the effect of compressibility of the working fluid by comparing the results of the proposed model to that of models that use incompressible flow assumptions together with Boussinesq approximation.

Calculation of a closed hydraulic volumetric system

2021 ◽  
pp. 27-30
Author(s):  
Keyword(s):  
Power Plant ◽  
Wind Power ◽  
Hydraulic System ◽  
Working Fluid ◽  
Wind Power Plant ◽  
Hydraulic Systems ◽  
Hydraulic Motor ◽  
Hydraulic Pump ◽  
Oil Pump ◽  
Selection Of

An algorithm is proposed for calculating a closed volumetric hydraulic pump-hydraulic motor system using the example of the hydraulic system of a wind power plant, based on the calculation of the hydraulic systems of mobile machines. The main characteristics of the system components, the selection of initial data for the calculation, working fluid and diameters of hydraulic lines are analyzed. Keywords: hydraulic system, energy, fluid, oil, pump, motor, renewable energy source, wind power plant, machine. [email protected]

Performance Analysis of a Solar-Assisted Organic Rankine Cycle

2020 ◽  
Author(s):  
M. T. Nitsas ◽  
I. P. Koronaki
Keyword(s):  
Mathematical Model ◽  
Performance Analysis ◽  
Temporal Variation ◽  
Storage Tank ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Evaporation Temperature ◽  
Solar Powered ◽  
The Mathematical Model

Abstract The objective of this paper is the thermodynamic analysis of a solar powered Organic Rankine Cycle (O.R.C.) and the investigation of potential working fluids in order to select the optimum one. A dynamic model for a solar O.R.C. with a storage tank, which produces electricity is developed. The mathematical model includes all the equations that describe the operation of the solar collectors, the storage tank, the Rankine Cycle and the feedback between them. The model runs for representative days throughout the year, calculating the net produced energy as a function of the selected evaporation temperature for every suitable working fluid. Above that, the temporal variation of the systems’ temperatures, collectors’ efficiency and net produced power, for the optimum organic fluid and evaporation temperature are presented.

scholarly journals Learning the basics of a battery pack control system

2020 ◽  
Vol 164 ◽  
pp. 13006 ◽  
Author(s):  
Kirill Kobzev ◽  
Sergey Vyalov ◽  
Alexander Rybak
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Numerical Experiment ◽  
Structural Parameters ◽  
Operation Mode ◽  
Power Source ◽  
Design Parameters ◽  
Hydraulic Systems ◽  
Original Design ◽  
Functional Features

The article discusses the control system of a hydraulic power source of constant pressure, which is a pump-storage power source, equipped with the original design of the automatic unloading of the hydraulic pump, which provides relay switching of its operation mode. A mathematical model is proposed, obtained using a modeling technique based on the application of the theory of volumetric rigidity of hydraulic systems and their elements. The results of a numerical experiment carried out by numerically solving the equations that make up the mathematical model of a power source are also presented. As a result of a numerical experiment, the main technical capabilities of the considered power source and the influence of its main structural parameters and functional features of the system on operational properties are revealed. The results showed that due to changes in various design parameters of the unloading machine, you can not only change the upper (maximum) and lower (minimum) values of the battery charging pressure, but also adjust their difference depending on the requirements for the power source. The main property of a power source with an automatic unloading device of the proposed design, confirmed as a result of a numerical experiment, is that the automatic unloading device provides a clear relay switching of the pump operation mode from unloading to operating mode and vice versa. The revealed properties make it very promising to use a pump-accumulator power source in the hydraulic systems of mobile machines and technological equipment.

scholarly journals Review of existing and development of a novel mathematical model for supercritical CO2 cycles working fluid

2018 ◽  
Vol 240 ◽  
pp. 01036
Author(s):  
Marcin Wołowicz ◽  
Jarosław Milewski ◽  
Piotr Lis
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Mathematical Model ◽  
Heat Capacity ◽  
Supercritical Co2 ◽  
Pressure Range ◽  
Critical Conditions ◽  
Working Fluid ◽  
Critical Properties ◽  
Area Of Interest

The paper aims to compare the models of working fluids against experimental data for carbon dioxide close to its critical conditions. Fortunately, most of the work is already done and published where the authors compared the models based on the equation of the state (EoS). There are a few other models which were not investigated, thus we would like to add a few new results here and focus only on near-critical properties where the biggest deviation between experimental and calculated properties can be observed. The area of interest was pressure range of 7.39 – 20 MPa and temperature range of 304-340 K just above fluid critical point (7.39 MPa, 304.25 K). Model validation was performed for density and heat capacity as one of the most important parameters in preliminary cycle analysis.

scholarly journals HFO1234ze(e) As an Alternative Refrigerant for Ejector Cooling Technology

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4045
Author(s):  
Van Vu Nguyen ◽  
Szabolcs Varga ◽  
Vaclav Dvorak
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
The Other ◽  
Coefficient Of Performance ◽  
Fourth Generation ◽  
Working Fluid ◽  
Third Generation ◽  
Alternative Refrigerant ◽  
Overall Performance ◽  
Cooling Technology

The paper presented a mathematical assessment of selected refrigerants for the ejector cooling purpose. R1234ze(e) and R1234yf are the well-known refrigerants of hydrofluoroolefins (HFOs), the fourth-generation halocarbon refrigerants. Nature working fluids, R600a and R290, and third-generation refrigerant of halocarbon (hydrofluorocarbon, HFC), R32 and R152a, were selected in the assessment. A detail mathematical model of the ejector, as well as other components of the cycle, was built. The results showed that the coefficient of performance (COP) of R1234ze(e) was significantly higher than R600a at the same operating conditions. R1234yf’s performance was compatible with R290, and both were about 5% less than the previous two. The results also indicated that R152a offered the best performance among the selected refrigerants, but due to the high value of global warming potential, it did not fulfill the requirements of the current European refrigerant regulations. On the other hand, R1234ze(e) was the most suitable working fluid for the ejector cooling technology, thanks to its overall performance.

scholarly journals Economic and theoretical study of the power supply from a pump-battery based on a discharge machine

2020 ◽  
Vol 175 ◽  
pp. 05042
Author(s):  
Kirill Kobzev ◽  
Sergey Vyalov ◽  
Alexander Rybak
Keyword(s):  
Mathematical Model ◽  
Numerical Experiment ◽  
Structural Parameters ◽  
Operation Mode ◽  
Power Source ◽  
Design Parameters ◽  
Hydraulic Systems ◽  
Original Design ◽  
Functional Features ◽  
Pump Storage Power

The article discusses the control system of a hydraulic power source of constant pressure, which is a pump-storage power source, equipped with the original design of the automatic unloading of the hydraulic pump, which provides relay switching of its operation mode. A mathematical model is proposed, obtained using a modeling technique based on the application of the theory of volumetric rigidity of hydraulic systems and their elements. The results of a numerical experiment carried out by numerically solving the equations that make up the mathematical model of a power source are also presented. As a result of a numerical experiment, the main technical capabilities of the considered power source and the influence of its main structural parameters and functional features of the system on operational properties are revealed. The results showed that due to changes in various design parameters of the unloading machine, you can not only change the upper (maximum) and lower (minimum) values of the battery charging pressure, but also adjust their difference depending on the requirements for the power source.

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