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Experiments have been performed to investigate the efficiency of the process of thermostabilization of a high-temperature surface with dispersed flow of a heat transfer agent at a pressure of 0.2–0.6 MPa in it and at a mass rate of flow of heat transfer agent of (3.3–6.15)·10–3 kg/s and a surface sprinkler density of 1.67–3.11 kg/(m2·s). Assessments have been made of the amount of heat transfer agent evaporating in all investigated heat transfer regimes. An equation describing various heat transfer regimes has been obtained for heat transfer from a high-temperature surface to a dispersed flow of a heat transfer agent in a criterial form. Criterial equations qualitatively describe experimental data within a small error, which indicates their satisfactory reproducibility in the said range of regime parameters of the process. [ABSTRACT FROM AUTHOR]

The development of in-chamber elements of a tokamak thermonuclear reactor is associated with a large number of challenging engineering problems, one of which is the removal of heat flows with a specific density of 10–20 MW/m2. Results of an experimental study of cooling by a two-component dispersed coolant flow directed perpendicular to the cooled surface are discussed. The study is a continuation of the research on enhancing the heat removal efficiency. The efficiency of this cooling method is due to a decrease in the proportion of convective heat transfer and an increase in heat exchange during evaporation. It is shown that the use of a two-component dispersed coolant flow makes it possible to remove heat flux densities exceeding 10 MW/m2 at a pressure of the coolant components not exceeding 0.5 MPa; the effect of the ratio of components on the efficiency of heat removal is investigated. The experimental data obtained indicate the high efficiency of the proposed cooling method. The heat transfer coefficient was found to reach 200 kW/(m2 K), a value which is significantly higher than that for conventional cooling methods based on single-phase water flow. [ABSTRACT FROM AUTHOR]

Pressure intensifiers have their utilization in hydraulic circuits, when there is a need for pressure multiplication for some period of time. Using intensifiers provides energy savings, cost reductions or smaller dimensioning. This article is about a pressure intensifier based on rotary flow dividers. Its functioning is evaluated by its pressure-multiplying efficiency. This efficiency is always calculated from values gained from measurements. However, it would be very convenient to be able to evaluate these types of intensifiers without a need to provide specific measurements for every type of intensifier and rather calculate their efficiency using the general parameters of a hydraulic circuit. Therefore, this article is about the description of a model which calculates the pressure-multiplying efficiency only with two input values: the pressure and the speed of an intensifier. Final derived formulas are also used for the efficiency prediction at pressure levels never measured before and then verified by measurements. [ABSTRACT FROM AUTHOR]

This paper presents the experimental research of factors influencing the UDS 214 excavator efficiency. The hydraulic oil flow rate is measured in hydraulic circuits for controlling the moving of the bucket of the UDS 214 excavator. From the measured values, the total power losses of the individual hydraulic circuits and their efficiencies are evaluated by calculations and measurements. Furthermore, the times of the excavator cycles during a soil excavation and loading of the transport vehicle were measured. From the measured operating cycle times of the excavator, the average value of the operating cycle time was evaluated and, from this average time, the theoretical performance and the operating performance of the given excavator in the given operational states were calculated. Then, at the end of the paper, the individual calculated power losses as well as the efficiencies of the hydraulic circuits for controlling the moves of the excavator are evaluated. According to the findings, the swing hydraulic circuit of the excavator, which has the second highest power loss of 5.926 kW and its percentage in the average tested cycle time of the excavator is 48%, seems to be a suitable hydraulic circuit for the innovation. [ABSTRACT FROM AUTHOR]

Selection of the cooling method for energy stressed elements, such as the divertor, limiter, and blanket, upon impact of powerful heat flows is an important issue for all research fusion reactors. At present, these elements are cooled by water under pressure, which can involve serious problems in an emergency situation related to poor tightness of elements of cooling system. This work considers an alternative cooling method of such structural elements using a two-component dispersed flow of coolant. Heating of the working segment under conditions close to stationary loads of the ITER first wall has been simulated at the test bench of the Department of General Physics and Nuclear Fusion of the National Research University Moscow Power Engineering Institute. Cooling of the working section is performed by dispersed flow of coolant over the inner surface. The temperature distribution over the wall thickness of working section has been obtained. The thermal conductivity of the material of the working section has been assessed. It is demonstrated that the proposed cooling method makes it possible to perform efficient heat removal under thermal loads in the range of 0.7–3.2 MW/m2. [ABSTRACT FROM AUTHOR]

A set of activities aimed at upgrading an experimental bench simulating heavily loaded components of thermonuclear facilities is accomplished. The design of a test section for implementing one-sided heating with high energy density is developed. A VCh-60AV high-frequency generator with operating frequencies of 30–60 kHz is the test section heating system's key component. The article describes the experimental bench schematic design, hydraulic circuit components, and the high-frequency heating system and measurement system components. The schematic design of a hydraulic atomizer with a conical insert, which generates a sprayed flow in carrying out experimental studies is presented. The results of field velocity measurements in the atomizer spray jet and of experimental study of sprayed flow distribution over the droplet radius are given, and the average diameter of droplets in the spray jet section was determined, which was found to be 34 μm. The techniques for carrying out experiments on thermal stabilization in a steady mode by spray cooling and for processing the primary experimental data are described. The effectiveness of high-temperature surface thermal stabilization by a spray of distilled water at a coolant gauge pressure of (0.2–0.6) × 106 Pa, coolant mass flowrate (3.3–6.15) × 10–3 kg/s, and spray density within the range from 1.67 to 3.11 kg/(m2 s) is studied. The obtained experimental data array is processed, and the graphic dependences of heat flux and heat-transfer coefficient on the temperature difference between the cooled wall and coolant spray are presented. The heat flux in the experimental study reached 3.2 MW/m2, and the heat-transfer coefficient in that case was equal to 77 kW/(m2 K). The obtained experimental data show satisfactory repeatability in a wide range of temperature difference from 0 to 400°C, and high heat flux and heat-transfer values have been reached. [ABSTRACT FROM AUTHOR]

Pressure intensifiers are used in specific areas of a hydraulic circuits, where increased pressure is needed, while the rest of the circuit (up to the pump) run on lower level of a working pressure. That could lead to a cheaper design of the components, while just one high pressure branch is designed on high pressure. Using pressure intensifier could also mean energy cost reductions. Rotary flow divider can be also used as a pressure intensifier. This area started to be developed in Jihostroj a.s. This paper describes specific tests, which has been running to precisely parameterize limits of use of a divider as an intensifier without design changes to follow with a development of a designs to maximize intensifier's parameters. Development also leads to compact solutions compatible with LS signals or with other hydraulic components to create compact assembly comparable to some areas of use of a piston pumps or inexpensive flow control drive. These development opportunities are also described in this paper. [ABSTRACT FROM AUTHOR]

The article refers to the proposed test equipment used to monitor the service life of hydrostatic transducers and fluids under constant or dynamic operating pressure loading. The proposed laboratory test equipment enables simultaneous testing of hydrostatic transducers and energy carriers in two hydraulic circuits and is designed to measure the flow characteristics and technical life of hydrostatic transducers with different energy carriers. The benefit of the proposed device is the possibility of simultaneous testing of the transducers as well as the performance of verification measurements of individual circuits, which was preceded by the development of a theoretical design. This includes the calculations necessary to determine the power of the drive, the cooling power as well as the definition of other parameters and elements of the hydraulic system. The design of the device was based on technical characteristics, load characteristics obtained by own measurements, and characteristics of individual hydraulic and electrohydraulic elements. On the basis of the prepared laboratory test equipment, it is possible to significantly shorten the time of operational tests and perform repeated tests under the same operational load with different types of energy carriers. The hydraulic circuit (primary or secondary) can be loaded through a proportional electrohydraulic pressure valve, which is able to simulate the load with the operational pressure curve obtained by measurement, as well as the cyclic stress, the frequency, amplitude, and rate of increase of which can be defined according to the selected methodology. A verification measurement of the flow characteristics of the used transducers was also carried out, which confirmed the correct function and design of the test laboratory equipment. The achieved results can be used in mechanical engineering for the accelerated life test of hydrostatic transducers, which are often used in mobile energy devices working in environmentally sensitive areas. The proposed laboratory test equipment will be used for testing ecological energy carriers, increasing the efficiency of energy conversion in agricultural facilities using biomass. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mechanical Engineering / Revista de Ingeniería Mecánica is the property of ECORFAN-Mexico S.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

At present, Mosenergo is carrying out computations and experiments to substantiate the possibility of reducing the minimum load for a group of natural-gas fired boilers (live steam pressure = 130 kgf/cm2) and ensuring continuous, without restrictions, operation of the main and auxiliary equipment. According to the operating documentation, the minimum load of Mosenergo boilers is 50 to 60%. To preliminarily assess the minimum permissible load, thermal and hydraulic analyses were carried out using specially developed mathematical models. To confirm that boilers can operate at a reduced load, to adjust the operating modes, and to determine the performance indicators, tests at various Mosenergo boilers were conducted. In the tests, the load of these boilers (TGME-464, TP-80, TP-80M, TP-87, TGM-84B, TGM-96) was reduced to 40 – 45% of the rating while maintaining the required reliability criteria, permissible environmental performance, and rated steam parameters. [ABSTRACT FROM AUTHOR]

By simulating the operating conditions, it is possible to verify and evaluate the technical properties of motor vehicle oil filters and the functionality of the designed equipment. Contaminated engine oil from operation was used with MANN W950/26 oil filter and a CNH Industrial 2992242 oil filter in the test circuit. Before use, the level of engine oil contamination in the test circuit was determined by evaluating the physicochemical properties. The laboratory test equipment also allows monitoring the technical life of oil filters, with variously contaminated engine oil, with the possibility of extending engine oil change service intervals depending on changes in the physicochemical properties of engine oil and filter efficiency. These laboratory tests can be performed in parallel in two hydraulic circuits, which can significantly reduce the testing time of the filter capabilities of oil filters, without the risk of engine damage, provided that the tests were performed under operating conditions. The results of the evaluation of the filtration capacity of oil filters can be used in the design of new filter materials, but also with a suitably determined methodology of oil filter replacement and engine oil change interval, it is possible to extend replacement intervals, which has a significant benefit not only from an economic but also ecological point of view. The result of the measurements is the confirmation of the functionality of the device with the possibility of simulating the operating conditions, at different degrees of oil contamination, at different operating temperatures and using different oil filters. [ABSTRACT FROM AUTHOR]

The main aim of the article is to present the design of laboratory test equipment, which is appropriate for monitoring the efficiency of oil filters and the system for evaluating the technical life of engine oils in terms of possible extension of service intervals. The functionality of the designed laboratory test equipment for the filtration of motor oils was verified by a practical experiment with a verification measurement and assessment of the suitability of the hydraulic circuit elements and the designed sensing equipment. The laboratory equipment enables the testing of oil filters with different filtration capacity during simultaneous testing in two separate hydraulic circuits with differently contaminated engine oil, while it enables laboratory measurements to be performed while simulating operating conditions. [ABSTRACT FROM AUTHOR]

In co-simulation, a number of subsystems sharing details of a system, are coupled to exchange data. The subsystem level development of each package enhances the computational efficiency, and more sophisticated packages can be created. However, the data exchange is not always straight forward as different packages can be developed by different research or industrial centers. Therefore, some standards such as Functional Mock-up Interface (FMI) are developed to facilitate the data exchange in co-simulation or co-integration. In this work, the co-simulation approach is employed to investigate the effects of dissolved air on the dynamic performance of a hydraulically driven multibody system. To this end, the subsystems of multibody system dynamics and a hydraulic model are coupled by using the FMU procedure. The utilized FMUs are produced by using an XML model description and a C code for the hydraulic part. The multibody mechanism under investigation is a jib crane model containing three bodies. The model is studied by exciting different sine inputs having known frequencies while varying the amount of dissolved air in the hydraulic system. The results have illustrated that by increasing the amount of entrained air, the pressure amplitude decrease. In addition, the results demonstrated that the amount of the air does not have effects on shifting the system frequency. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Jiangsu University (Natural Science Edition) / Jiangsu Daxue Xuebao (Ziran Kexue Ban) is the property of Editorial Department of Journal of Jiangsu University (Natural Science Edition) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work presents a new concept of fine position control of vehicle lift systems used for maintenance services, to facilitate specialized tasks such as height balancing of tilted vehicles. The research goal is accomplished by utilizing a controllable hydraulic circuit associated with magnetorheological valves. After establishing the required dynamic forces and position control range of the vehicle's lift system, a two-coil type of magnetorheological valve is designed with consideration of the field-dependent properties of the magnetorheological fluid and the magnetic flux intensity, which is analyzed using the finite element method. Magnetorheological valves are then manufactured and the pressure drops are evaluated as a function of the input current (magnetic field). A hydraulic circuit with magnetorheological valves is formulated to control the height of the lift with an accuracy of ±1 mm with a load of 2000 kg on the each lifts. It is experimentally demonstrated that ramp and sinusoidal positions (or height) are well tracked within the targeted accuracy by controlling the magnetorheological valves. In addition, it is shown that the tilted position of the loaded vehicle with an eccentric mass placed on the lift is well controlled showing the balanced height. [ABSTRACT FROM AUTHOR]

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Three filtration systems using the tractor hydraulic circuit were proposed and verified during the tractors operation. Using the tractor-implement hydraulic system and filter body with accessories the universally useful filtration systems were designed. The designed filtration systems are the second stage of universal oil filtration whereas the first stage is the standard tractor filter. The decrease in the content of iron reached the values 25.53%, 32.95% and 41.55% and the average decrease in oil contamination characterized by average value of decrease in content of iron, copper and silicium reached values 24.3%, 24.7% and 35.53% in dependence on the filtration system and an oil contamination level. The decrease in contamination level verified the ability of designed filtration systems for agricultural tractors. [ABSTRACT FROM AUTHOR]

There are different mechanical presses used to deform or press the material through dies to convert into useful product by applying different conditions like temperature, pressure, speed of ram etc. These material deformation techniques not only used to produce finished products but also to increase the strength of the material by introducing severe plastic deformation. Equal channel angular pressing (ECAP) is a technique used to increase the strength of materials by introducing severe plastic deformation through grains refinement. The ECAP die consisting of two channels intersecting at 90 degree was designed and manufactured to perform angular extrusion. The load was calculated through mathematical modelling. A hydraulic press equipped with conventional temperature control furnace, sensor based limit switches, pressure controlled mechanism and with variable speed control was designed, fabricated and manufactured at UET Taxila. The material used for the fabrication purposes is mild steel. The major designing parameters included stroke length, maximum load, pressure, cylinder bore, sealing mechanism and volume flow rate of working fluid. The main parts of the hydraulic press consist of piston and cylinder arrangement, structure or frame, press stand and hydraulic circuit. The press was tested initially for its leakage and then test was performed on Teflon and Nylon materials at 2 tons of pressure. Later on the aerospace grade aluminum alloy 6061 was pressed through ECAP die at a speed of 9mm/sec. [ABSTRACT FROM AUTHOR]

This paper deals with a methodology for measuring and evaluating the static characteristics of control valves, with specifying a recommended measurement chain. This method enables measuring and evaluating the dependence of pressure drop on flow and flow coefficients depending on the type of fluid, temperature and viscosity also if the measurements were made at a different temperature and viscosity. This method extends of the possibility of using of these characteristics in the design work on hydraulic components in various areas of operation. [ABSTRACT FROM AUTHOR]

The entire hydraulic circuit of a mid size power agricultural machine (New Holland T6000 of CNH Industrial) has been studied in this paper using a lumped parameter approach, in Siemens LMS AMESim® environment. The analyzed circuit has been split in two main units: the fluid power supply unit and the high pressure circuit with users. The first one converts the inlet mechanical power into hydraulic power, while the third one converts hydraulic power in mechanical power. Each unit has been separately modeled and validated comparing the simulation data of each block with the experimental data provided by the manufacturer. The proposed target of each simulation has been achieved with a good accuracy. The model has been run in several tests where the load has been modeled using a valve and an orifice with fixed section. Tests have been run combining the fluid power supply unit and the high pressure circuit with users. In the final model, the priority valve has been modeled using three different loads called Load 1, Load 2 and Load 3. Each load simulates a user, therefore Load 1, 2 and 3 are respectively the steering, the trailer brake valve and the rest of the circuit. The model demonstrates that it is possible to predict, in a simple way, the real working conditions of the hydraulic circuit. This research has demonstrated that the study of hydraulic circuits of agricultural machines using a lumped parameter modeling approach is a valid instrument that can help engineers to design new solutions for energy saving or power management of complex machines. [ABSTRACT FROM AUTHOR]

Moving liquids by industrial and domestic hydraulic circuits annually requires tens of billions of kilowatts of electricity per hour. Today there is not any universal indicator that would characterize generalized conversion efficiency of electrical energy into hydraulic and efficiency of using of hydraulic energy. This greatly complicates the optimization of the hydraulic circuit parameters on energy criterion in its design or testing calculation. Aim: The aim of the research is to assess the losses in the discharge equipment of hydraulic circuits, as well as in pipeline through the introduction of common indicator of the effectiveness of transporting liquid. Materials and Methods: We show that specifications for energy efficiency of hydraulic circuit it is not enough the pumping efficiency of the installation, or calculate the efficiency of individual elements of the hydraulic circuits. To achieve the goal asked to enter the energetic coefficient of energy perfected circuit, which is the ratio of output flow power from the hydraulic circuit to the flow power on the pump shaft. Results: The proposed coefficient takes into account the loss of pressure in the pump and in the pipeline and provides an objective assessment of the energy efficiency of the circuit; in addition, it allows you to compare the energy perfection of hydraulic systems with different parameters and different pumps. The proposed coefficient should be used in the design of hydraulic circuits and during the checking calculation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We consider mathematical models of the operation of pipelines with automatic flow regulators installed on several sections. We present a system of equations and inequalities that describes the flow distribution in such pipelines. We prove that the stated system gives optimality conditions for two mutually dual convex programming problems. This enables us to obtain conditions for the unique existence of a solution to this system. [ABSTRACT FROM AUTHOR]

This paper aims to study how the flow behaves in key elements of small hydropower plants (SHP) which should be well designed in order to achieve properly the best hydraulic and energy efficiency. There are some hydrodynamic and structural fundaments that all hydro circuits design has to follow, and there are other aspects that vary from design to the flow behavior. The variables that influence the hydro systems design are related with performance, technical, operational and environmental aspects. For instance, design discharge, produced energy, intakes and outlets geometry are some of the technical variables. The components of SHP design should be characterized by a balance between hydraulic, structural, operational and environment efficiency and economic issues. To improve the hydraulic efficiency is necessary information concerning with hydrodynamic flow behavior. The knowledge in this area is still insufficient since the hydrodynamic flow patterns, in some key elements of hydraulic circuits of SHP are quite complex. Therefore this paper uses an advanced computational fluid dynamic (CFD) model for flow simulation, with the aim to improve the behavior comprehension enabling the identification of parameters' variation which influences the performance efficiency of those components in the design criteria of such SHP. Since the inefficiency and the unsafe operating conditions are normally associated to separated flow zones, vorticity development, macro turbulence intensity, pressure gradients, shear stress increase, this paper intends to analyze causes and consequences of the flow behavior. Among these concerns it is possible to identify induced problems, such as vibrations, resonance effects, ruptures or collapses, cavitation, water column separation, significant friction losses, vortices and regions of reversed flow. [ABSTRACT FROM AUTHOR]

X-by-wire control systems in automotive applications refer to systems where the input device used by the operator is connected to the actuation power subsystem by electrical wires, as opposed to being connected by mechanical or hydraulic means. The "X" in the X-by-wire is replaced by "steer", "throttle", and "brake" to represent the steer-by-wire, throttle-by-wire, and brake-by-wire systems. Common to all of these subsystems is that the operator control input device (i.e., steering column, acceleration pedal, and brake pedal) is not connected to the actuation devices mechanically. Rather, it is connected to an embedded computer which, in turn, sends the control signals to the actuation devices. Current state of art steering systems used in articulated vehicles are hydro-mechanical type systems, i.e., the steering column motion is transmitted and amplified by the main hydraulic circuit by hydro-mechanical means. This paper presents a new steer-by-wire (SBW) system which we designed, modeled, analyzed, and tested on wheel type loader construction equipment. The simulation results and tests conducted on a prototype development vehicle (a medium size wheel type loader) show very good agreement. The control algorithm is modeled using graphical modeling tools similar to Simulink and StateFlow. A real-time control algorithm is implemented on a Motorola 68332 microprocessor-based embedded controller. The operational performance of the steer-by-wire system has been convincingly demonstrated. [ABSTRACT FROM PUBLISHER]

The InWave wave energy converter (WEC), which is three-tether WEC type, absorbs wave energy via moored cylindrical buoys with three ropes connected to a terrestrial power take-off (PTO) through a subsea pulley. In this study, a simulation study was conducted to select a suitable PTO when designing a three-tether WEC. The mechanical PTO transfers energy from the buoy to the generator using a gearbox, whereas the hydraulic PTO uses a hydraulic pump, an accumulator, and a hydraulic motor to convert mechanical energy into electrical energy. The hydraulic PTO has a lower energy conversion efficiency than that of the mechanical PTO owing to losses resulting from pipe friction and the individual efficiencies of the hydraulic pumps and motors. However, the efficiencies mentioned above are not the efficiency of the whole system. The efficiency of the whole system should be analyzed considering the tension of the rope and the efficiency of the generator. In this study, the energy conversion efficiencies of the InWave WEC installed the mechanical and hydraulic PTO devices are compared, and their behaviors are analyzed through numerical simulations. The mechanics of mechanical and hydraulic PTO applied to InWave are mathematically expressed, and the issues of the elements constituting the PTO are explained. Finally, factors to consider for PTO selection are presented. [ABSTRACT FROM AUTHOR]

This paper proposes generalized models and methods for calculating flow distribution in hydraulic circuits with lumped parameters. The main models of the isothermal steady-state flow of medium are classified by an element of the hydraulic circuit. These models include conventional, implicitly specified by flow rate, and pressure-dependent ones. The conditions for their applicability, which ensure the existence and uniqueness of a solution to the flow distribution problem, are considered. We propose generalized nodal pressure and loop flow rate methods, which can be applied regardless of the forms of specific element models. Final algorithms, which require lower computational costs versus the known approaches designed for non-conventional flow models, are substantiated. Proposed models, methods, algorithms, and their capabilities, are analytically and numerically illustrated by an example of a fragment of gas transmission network with compressor stations. [ABSTRACT FROM AUTHOR]