Hydraulic Circuit Research Articles

Design and implementation of a series hydraulic hybrid propulsion system to increase regenerative braking energy saving range

Environmental contamination has prompted researchers to offer approaches and solutions in a variety of fields, including hybrid drive train. A novel series hydraulic circuit for a regenerative braking system has been presented in order to expand the energy-saving range of regenerative braking and remove friction braking. In various driving scenarios, the generated hydraulic torque performs deceleration. On the basis of the type of deceleration, the single and dual braking modes are examined. In the single braking mode, the required torque is produced by a change in pump output flow, but in the dual braking mode, the torque is provided by simultaneous changes in flow and pressure. The controllers are applied to change the pump output pressure and flow based on the braking mode. Due to the existence of numerous situations for parameters influencing the choice of braking method and the significant difference in the amount of recovery energy in two scenarios an artificial neural network has been employed to decide between single and double braking. To validate the suggested model, a setup for experimentation has been created to simulate various circumstances. Compared to conventional circuits, the modification to the hydraulic circuit increases the initial cost and complexity of the control structure andmaintenance. The evaluation of braking performance and the amount of energy stored under various braking conditions resulted to an average energy storage of 63 percent in single braking mode and 17 percent in dual braking mode. The maximum speed error in single braking is 3.5 at 60 RPM and 7 at 132 RPM in double braking. Thus, the maximum speed error during single and double braking is 5.8 and 5.3 percent, respectively. Unlike typical hybrid systems, all braking conditions resulted in the storage of energy.

Experimental and Modelling Analysis of a Downstream Compensation System: Energy Optimization of the Directional Control Valves

Through a study on the Fluid Power innovations in the last years emerged that still few solutions have been successfully implemented for the optimization of the hydraulic circuits. The recent machine electrification offers a potential for investment in energy-saving hydraulic systems to ensure greater performance and higher battery autonomy. From different studies emerged that in the specific field of ICE Off-road Vehicles, only about 10–15% of the available power at fuel level is actually transformed into useful energy for the actuators. Particularly the losses in the Directional Control Valves represent about 35–40% of the hydraulic energy available at the pump level. The traditional Directional Control Valves design solutions, in fact, neglects important opportunities for reducing losses and improving internal regeneration. Especially, energy recovery is rarely applied and in any case by means of important superstructures which considerably increase the costs of the system. This paper presents a new hydraulic architecture: an original Directional Control Valve layout based on a Downstream Compensation approach. In particular, a Flow Sharing system is implemented in this new architecture with the goal to minimize the wasted energy. In fact, this system realizes an important energy recovery from both the inertial loads and the simultaneous use of multiple actuators at different pressure level. The circuit enables recovered energy to be stored in a high-pressure accumulator. The paper presents the simulation results and the energy saving estimation realized through a lumped parameter environment “Amesim Simcenter”. Additionally, the results of experimental activities show the innovative system performance, benefits and physical applicability. This idea is based on concrete objectives and pays particular attention to cost sustainability, industrial manufacturability and system scalability.

Influence of the excavator hydraulic system efficiency on the productivity

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.

Prediction of Temperature Behavior in Hydraulic Circuits

The increasing complexity of products and systems in modern engineering production requires higher demands on the operation and maintenance of systems. For this reason, the role of maintenance can hardly be underestimated, as the maintenance of machinery and equipment is an integral part of any manufacturing process. Maintenance is closely related to the precision of the parts produced and the quality of the manufacturing process. A current trend in Industry 4.0 is predictive maintenance, which enables real-time detection of faulty equipment conditions based on condition monitoring. Utilizing artificial intelligence for predictive analytics can considerably contribute to the prediction of potential failures. Consequently, maintenance costs related to production downtime and equipment repair will be decreased. In this paper, a non-linear autoregressive neural network for real-time prediction of working fluid temperature parameters in a hydraulic circuit is presented. A testing device is also developed to collect experimental data, optimize, and test the proposed prediction model.

Application of methods for modeling hydraulic and non-isothermal steady states of gas transmission systems

In the article, for the first time, an attempt was made to justify the effectiveness of the application of new generalized methods of the theory of hydraulic circuits for modeling stationary modes of operation of gas transmission systems of complex structure and configuration. A classification of the main models of a steady gas flow is given for individual elements of the system, including traditional ones, those implicitly specified in terms of flow rate and dependent on the pressure of the working medium. Generalized flow distribution models are proposed that take into account all these cases. Conditions for the applicability of generalized methods that ensure the existence and uniqueness of the solution to the flow distribution problem are considered. The characteristics of these methods and final algorithms are given, which provide confident convergence and require less computational costs compared to existing methods. Numerical examples illustrating such possibilities are given.

Application experience of the theory hydraulic circuits methods and modern technologies for organizing operating conditions of Mongolian district heating systems

An analysis of the district heating systems (DHS) current state in Mongolia and the problems of their functioning is given. The experience of applying the theory hydraulic circuits methods and the informationcomputer complex «ANGARAHN» developed at the ISEM SB RAS for modeling and organizing the operating conditions of the Mongolia DHS is given. Ways have been outlined to improve the reliability, efficiency and quality of DHS work. The tendencies, directions and possibilities of overcoming the existing problems in operating conditions control are outlined. including, - the development of scientific, methodological and software for solving new problems of operational control (monitoring the state, calibrating models, active identification and optimization of modes) based on the creation of a common digital space.

Electrothermal System Design and Evaluation of Low EMI and Thermally Balanced 150 kW T-Type Traction Inverter

Power electronics switching devices utilized in traction, propulsion, and power generation applications require advanced thermal management systems and extensive electromagnetic interference filtering components. The traditional indirect cooling methods exhibit limited ability to target switching location hotspots, causing limited cooling capabilities and thermal imbalance. Additionally, they rely on metallic structures directly integrated with module base plates, allowing for an accentuation of common-mode noise. These effects present themselves concurrently, creating reliability concerns while requiring further noise filtering. This work demonstrates the integration of a nonmetallic jet impingement cooler for direct base plate thermal management of a 150 kW silicon-carbide inverter. The use of nonmetallic structures manufactured through additive techniques limits low-induction capacitance pathways by 99%, leading to a 25 dB reduction in common-mode noise. Impingement jets focused on module hotspots reduce maximum device temperatures and increase thermal uniformity. Finally, by attaching individual jet coolers to each power module, hydraulic circuit networks are used to demonstrate thermal balancing between power devices for optimal current sharing.

Design and fabrication of a bioreactor for the proliferation of mesenchymal stem cells

Currently, the number of organ donors is low and there are different methods to deal with this situation, including cell cultures, decellularization and bioreactors, which play an important role in helping the required processes to be carried out in a faster and more optimized way. The objective of this work is to make the cell proliferation process efficient using a bioreactor as an alternative, in which flow simulations can be made to previously analyze how it works. The radial flow hydraulic circuit was designed and simulated in SOLIDWORKS solving Navier-Stokes equations to verify that we have a non-turbulent laminar flow and simulate cell detachment without damaging the cell matrices. The design was printed with additive printing techniques, using photosensitive resin. Bioreactors also play a part in tissue engineering, as they allow for changes that can be monitored and reproduced in particular environmental factors. This article shows the successful design of a bioreactor to proliferate mesenchymal stem cells printed and subjected to simulations, whose results lead to the conclusion that there is non-turbulent laminar flow in the behavior of the system without subjecting the cells to a possible stress that causes damage.

Hydraulic characteristics of the convergent-divergent nozzle with the inner electrode in cavitating conditions

The knowledge of hydraulic characteristics of convergentdivergent nozzles will lead to the optimal design of a nozzle for generating a cavitation cloud. Such a nozzle is a crucial component of the CaviPlasma device, which aims to tackle the ever-growing water treatment and purification issue. To measure the characteristics, a closed hydraulic circuit was used to measure pressure differences before and behind the nozzle, and the flow rate. The characteristics were then developed based on the calculated loss coefficient ξ and the cavitation number σ. Three different nozzle designs were tested (with diameters of necks 3 mm, 4 mm, and 5 mm respectively), and multiple positions of the inner electrode were set for each design. This resulted in several characteristic curves for each design and electrode position. The study will contribute to the development of an optimal nozzle for the CaviPlasma device, enhancing its efficiency in water treatment and purification.

The current state of district heating processes in China and directions for the development of the methodological and instrumental base to support them

The article assesses the current state of district heating systems covering more than 100 cities in northern China. The main features of such systems, as well as the problems that arise during their design and operation, are disclosed. The relevance of the development and application of independent methods of mathematical and computer modeling to solve these problems is disclosed. As a methodological basis, it is proposed to use the modern achievements of the theory of hydraulic circuits developed at the Energy System Institute of the Siberian Branch of the Russian Academy of Sciences. The characteristics of the possibilities of the software tools available here are given. The main directions and prospects for the development of these scientific, methodological and software developments are disclosed.

Pressure Signal-Based Analysis of Anomalies in Switching Behavior of a Two-Way Directional Control Valve

Abstract Solenoid operated direction control valves, responsible for regulating the flow of fluid in hydraulic circuit highly relies on the control current for their actuation. The control currents supplied to the solenoid generate the electromagnetic force required for switching of valves by mechanical movement of spools inside. The deterioration in control current leads to the degradation in electromagnetic force and thus the spool takes longer to initiate as well as terminate the switching phenomenon. This delay or lag potentially causes the pressure, flow and power fluctuation, and unintended impacts on the system. This article presents a comparative analysis of detecting these anomalies by acquiring pressure signals across the valve using extreme gradient boosting (XGBoost) and one-dimensional convolution neural network (CNN). Four handcrafted statistical features and four fractal dimensions train XGBoost whereas 1D CNN with six hidden layers utilizes the raw signal of net pressure change across the valve. XGBoost predicts the switching behavior at an accuracy of 99.68%, and 1D CNN performs at its maximum possible accuracy (100%). The very narrow gap signifies the nearly equal significance of both of these different category classifiers. As XGBoost cannot handle the raw signals, the pre-processing increases the time consumption while 1D CNN does not require deep architecture and efficiently maps the complexity of the hydraulic system using pressure signals.

К ВЫВОДУ УРАВНЕНИЙ РЕГУЛИРОВАНИЯ И АНАЛИЗУ ОСОБЕННОСТЕЙ ГИДРАВЛИЧЕСКИХ РЕЖИМОВ ОТКРЫТЫХ СИСТЕМ ТЕПЛОСНАБЖЕНИЯ БЕЗ РЕГУЛЯТОРОВ РАСХОДА НА АБОНЕНТСКИХ ВВОДАХ

Energy efficiency and improved quality are currently very relevant issues in the housing and communal sector. These can be addressed, first of all, by introducing automated control systems and implementing optimized algo-rithms for monitoring and regulating heating and heat supply processes in general. The task of studying the features of the hydraulic regime of open heat supply systems without flow controllers at subscriber inputs is considered. Since a significant number of heating networks are open, the ban on their operation was reversed by Federal Law No. 438-F3 of December 30, 2021. Existing literature on open heating networks was analyzed and summarized. The hydraulic re-gime of open heating networks is very complex; its characteristic features are not sufficiently detailed and not clearly explained in the literature. This introduces difficulties in improving the quality of operation of open networks and uni-versity educational programs. In this paper, a detailed derivation of the main relationships characterizing the hydraulic regime is provided, with the assumption that the analyzed heat network is configured according to S.A. Chistovich’s ho-rizontal track principle. This makes it possible to reduce the calculation of a real operating network to a calculation of the hydraulic regime of a single-loop equivalent heat network using Kirchhoff’s laws for hydraulic circuits, which, un-like electrical circuits, are always non-linear circuits. The obtained solutions for specific cases were analyzed; in partic-ular, the influence of the water intake on the heating mode of consumers was studied for various characteristics of the heat supply system and outdoor temperature. The aforementioned algorithms can be used both for the algorithmic sup-port of automated heat supply control systems and for educational purposes.

Аnalysis of energy saving methods servic-ing airfields and airplanes

Problem. The problem is an integral part of developing the concept of forming a standard range of transport and technological hydrophilic modular means for maintenance of airfields and aircraft. Goal. The goal is development of scientifically sound recommendations for determining the rational parameters of the hydraulic system with automation of control and energy saving during operation of modular vehicles for maintenance of airfields and aircraft, taking into account the potential of domestic engineering and critical imports of units and assemblies. Methodology. The methods include analysis of energy saving methods in hydraulic fluid power of mobile machines according to manufacturers' catalogs and industrial examples taking into account the needs of modular vehicles for maintenance of airfields and aircraft, in particular, taking into account the creation of modern hydraulic devices and circuit solutions in hydraulic drives with throttle and machine control and automatic regulators of change of hydraulic fluid power. Results. It is established that in hydraulic drives with throttle control and pumps with unregulated working volume, throttles on parallel flow and three-wire flow regulators or LS and LUDV modern systems are used; automatic pressure and flow regulators are used with pumps with adjustable displacement; in machine-controlled hydraulic drives through the use of pumps and hydraulic motors with adjustable displacement and hydraulic automation; by energy recovery during operation and bench tests of hydraulic drives; at the design stage of hydraulic drives, when the static analysis is performed in terms of efficiency and dynamic to reduce the loads on the starting modes of operation; and also at designing lay the effective circuit technical decisions promoting energy saving; directly in operation due to high-quality working fluids, heat exchange systems and filtration. Originality. The classification of methods of energy saving in volumetric hydraulic drives of mobile machines is made and examples of application of some means which are planned for introduction in transmissions and the technological equipment of cars for service of aerodromes and planes are resulted. Practical value. The possibility of a rational selection of axial-piston domestic hydraulic machines for the development of hydraulic drives for airfields and aircraft is proven.

Analysis of modern technical means for servicing airports and airplanes

Problem. The problem is an integral part of developing the concept of forming a standard range of transport and technological hydrophilic modular means for maintenance of airfields and airplanes. Goal. The goal is development of scientifically sound recommendations for determining the rational parameters of the hydraulic system with automation of control and energy saving during operation of modular vehicles for maintenance of airfields and aircraft, taking into account the potential of domestic engineering and critical imports of units and assemblies. Methodology. The methods include analysis of energy saving methods in hydraulic fluid power of mobile machines according to manufacturers' catalogs and industrial examples taking into account the needs of modular vehicles for maintenance of airfields and aircraft, in particular, taking into account the creation of modern hydraulic devices and circuit solutions in hydraulic drives with throttle and machine control and automatic regulators of change of hydraulic fluid power. Results. It is established that in hydraulic drives with throttle control and pumps with unregulated working volume, throttles on parallel flow and three-wire flow regulators or LS and LUDV modern systems are used; automatic pressure and flow regulators are used with pumps with adjustable displacement; in machine-controlled hydraulic drives through the use of pumps and hydraulic motors with adjustable displacement and hydraulic automation; by energy recovery during operation and bench tests of hydraulic drives; at the design stage of hydraulic drives, when the static analysis is performed in terms of efficiency and dynamic to reduce the loads on the starting modes of operation; and also at designing lay the effective circuit technical decisions promoting energy saving; directly in operation due to high-quality working fluids, heat exchange systems and filtration. Originality. The classification of methods of energy saving in volumetric hydraulic drives of mobile machines is made and examples of application of some means which are planned for introduction in transmissions and the technological equipment of cars for service of aerodromes and planes are resulted. Practical value. The possibility of a rational selection of axial-piston domestic hydraulic machines for the development of hydraulic drives for airfields and aircraft is proven.

Integral Thermal Management Studies in Winter Conditions with a Global Model of a Battery-Powered Electric Bus

The potential of e-bus transportation to improve air quality and reduce noise pollution in cities is significant. In order to improve efficiency and extend the useful life of these vehicles, there is a growing need to investigate improvements for the thermal management system of electric city buses. In electric vehicles, there are several systems whose thermal behaviors need to be regulated, such as batteries, electric machines, power electronics, air conditioning, and cabin. In this study, a 0D/1D model of an electric city bus is developed that integrates all sub-models of the powertrain, auxiliaries, and thermal management system. This model is used to evaluate different configurations and thermal management strategies of the electric urban bus by simulating public transport driving cycles in Valencia, Spain, under winter conditions. First, the original thermal–hydraulic circuit of the bus was modified, resulting in an improvement in the battery energy consumption with savings of 11.4% taking advantage of the heat produced in the electric motors to heat the battery. Then, the original PTC heating system of the bus was compared with a proposed heat pump system in terms of battery power consumption. The heat pump system achieved an energy savings of 3.9% compared to the PTC heating system.

SPIRAL TURBINE CASING - IMPELLER ASSEMBLY DESIGN AND FLUID FLOW ANALYSIS

Turbine is a hydraulic engine where energy transfer occurs both based on the kinetic energy and potential (pressure) of the water. In this article we have designed the Spiral Turbine Casing – Impeller assembly with dimensions, geometry from technical documentation forms and the articles of other authors. CAD design of this assembly is a challenge and was done using .NX SIEMENS. The study of the fluid flow was done with ANSYS CFX by importing this assembly, some conclusions were drawn regarding the fluid velocities and the pressure field. The cavitation phenomenon that may occur in the operation of the turbine was also taken into account and some conclusions were drawn regarding the effects of this phenomenon. If the presence of vapours in the hydraulic circuit is found, then the cavitation can develop and this fact can be highlighted with Vapour Volume Fraction.

A new climate chamber for air-source and ground-source heat pump testing based on the Hardware-in-the Loop approach: Design and cross validation

The present paper describes a new test bench, designed for experimental tests on small- and medium-sized air-source and ground-source heat pumps, built at the University of Bologna (Italy). The test rig is based on the “Hardware-in-the-Loop” approach and is mainly composed of a test room (i.e. the climate chamber), in which the tested heat pump is placed, a borehole heat exchanger field for tests on ground-source units, the hydraulic loop and the building emulator. The test rig allows to test commercial and prototypal heat pumps under dynamic operating conditions, in order to reproduce the real behavior of a heat-pump based heating system and assess the heat pump effective energy performance. According to the Hardware-in-the-Loop approach, the hydraulic circuit of the facility is designed to reproduce exactly the time-dependent variations of the weather data during a series of representative days in a chosen site and the building thermal load given to the heat pump, calculated by a dynamic simulation software (i.e., the building emulator). In this paper, main components of the experimental facility are presented and the outcomes of a series of numerical simulations carried out with different software, such as Trnsys, Matlab-Simulink and STAR-CCM+, to define the system operative range and the effective behavior of the test bench under dynamic conditions are reported. Numerical models have been validated with experimental data, obtained from a trial test carried out on an air-source heat pump according to current technical standards. Comparison between numerical data and experimental results point out an excellent agreement and, for this reason, numerical models can be used to assess the optimal position of the tested heat pump within the chamber or to define the test bench operating conditions. The cross-validation methodology between experimental data and numerical results from different software, applied in this paper to a test bench for heat pumps, can be employed for the sizing of other test facilities.

A REVIEW STUDY IN TROUBLESHOOTING OF HYDRAULIC SYSTEMS IN CEMENT INDUSTRIES

Behind every hydraulic system there exists critical components that influence power transmission. To improve talent you should recognize how these components operate and affect the system i.e. learn the kinds of filter and piping used in hydraulic systems, describe the types and functions of hydraulic seals, and explain the operating principles of different types of pumps, and further learning the types and uses of accumulators, control valves, relief valves, cylinders, and even actuators. In this research study appropriate problem-solving processes are applied, and this helps to comprehend the hydraulic concepts and hydraulic schematic representations. Therefore, it will enhance the knowledge and the capacity of troubleshooting the different hydraulics systems in the cement industry. This will enable the person to stay on top of the industry practices in hydraulics, explore the basics of a hydraulic system by reviewing the types and properties of hydraulic fluids, identifying the symbols used on hydraulic schematic representations, and explaining hydraulic circuit operations based on a schematic design.

Design, Simulation, and Experimental Study on the Hydraulic Drive System of an AUV Docking Device with Multi-Degree Freedom

AUV docking devices have the ability to achieve homing of the AUV, supply the AUV with energy, and exchange data with it, thus improving the endurance and ensuring the continuous long-term and large-scale operation of the AUV. To improve the successful docking rate of the AUV, a funnel-shaped underwater docking device with multi-degree freedom based on a deep-sea platform was designed in this paper. The heading angle, pitch angle, and roller angle of the docking device could be adjusted in a timely manner according to the current flow direction and the position of the AUV. In order to realize the timely adjustment of the heading angle, pitch angle, and roll angle of the docking device, a set of underwater hydraulic systems was developed as the power source to drive the corresponding hydraulic cylinders, hydraulic motors, and other executive components. The model of the heading angle adjustment circuit of the hydraulic system was established and the open-loop transfer function of the heading angle adjustment circuit was derived. The dynamic response performance of the hydraulic circuit was simulated and the optimized PID algorithm was used to improve the dynamic response performance. Finally, the accuracy of the heading angle adjustment circuit model and the effectiveness of the control algorithm were validated by experiment of the docking device in a water pool.

Junction matters in hydraulic circuit bio-design of microfluidics

Junction matters in hydraulic circuit bio-design of microfluidics