scholarly journals IMPROVEMENT OF TECHNOLOGICAL EQUIPMENT OF THE MACHINE FOR TRIMMING TREE CROWNS IN ROADSIDE FOREST BELTS

2017 ◽  
Vol 7 (1) ◽  
pp. 205-210
Author(s):  
Попиков ◽  
Petr Popikov ◽  
Бухтояров ◽  
Leonid Bukhtoyarov
Keyword(s):  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Operating Conditions ◽  
Cutting Process ◽  
Design Parameters ◽  
Working Fluid ◽  
Hydraulic Motor ◽  
Technological Parameters ◽  
Tree Crowns ◽  
Circular Saw

When cleaning cutting, pruning of branches of roadside trees and shelter belt contour cutters are widely used, cutters is designed for total horizontal, vertical and oblique trimming crowns. These devices are hinged or removable ones and aggregated with wheeled tractors of traction class 0.6 to 1.4 kN, widespread in forestry. Improving the design of such devices is made in the following areas: cutting devices and hydraulic drives. In the proposed working body of the machine for cutting tree crowns containing base machine, crane on the handle of which a rotary hydraulic motor (rotator)is mounted, the shaft of which has movable connection with the housing of the circular saw with one-sided sharpening in the direction of the detachable part of the branch, V-shaped emphasis in the form of unilateral action hydraulic cylinder with spring-loaded rod, piston cavity which is connected in series with the drain lines of the hydraulic motor which is mounted an adjustable throttle to create pressure of the working fluid (support). In this implementation of the device when circular goes deep into the branch, which is cut, the V - shaped support with spring-loaded rod moves all the way in the branch and eliminates the clamping of the saw blade in the cut, which will improve reliability and performance. The article has developed a mathematical model of device for pruning tree crowns by circular saw with hydraulic drive on the basis of common methodology for the simulation of planar mechanisms. Differential equations of the cutting process were composed. The model of proposed design of the device for cutting tree crowns allows to study the influence of geometrical and mechanical parameters of the branches of the trees, technological parameters of cutting process on energy consumption and quality of the cut, taking into account design parameters. The model allows also to assess the performance and to examine the effectiveness of the device in different operating conditions.

Stabilization of the Speed of the Hydraulic Motor Through Throttle Compensation for Volume Losses

2020 ◽  
Vol 26 (3) ◽  
pp. 126-130
Author(s):  
Krasimir Kalev
Keyword(s):  
Flow Rate ◽  
Hydraulic Drive ◽  
Pressure Change ◽  
Operating Conditions ◽  
Drive System ◽  
Inlet Pressure ◽  
Schematic Diagram ◽  
Hydraulic Characteristics ◽  
Hydraulic Motor ◽  
Flow Through

AbstractA schematic diagram of a hydraulic drive system is provided to stabilize the speed of the working body by compensating for volumetric losses in the hydraulic motor. The diagram shows the inclusion of an originally developed self-adjusting choke whose flow rate in the inlet pressure change range tends to reverse - with increasing pressure the flow through it decreases. Dependent on the hydraulic characteristics of the hydraulic motor and the specific operating conditions.

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

2021 ◽  
pp. 1-38
Author(s):  
Noman Yousuf ◽  
Timothy Anderson ◽  
Roy Nates
Keyword(s):  
Waste Heat ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Factors Affecting ◽  
Thermally Driven ◽  
Mass Flowrate ◽  
Diffusion Absorption

Abstract Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

scholarly journals Justification of the Kinematic Diagrams for the Distribution System of a Planetary Hydraulic Motor

2018 ◽  
Vol 7 (4.3) ◽  
pp. 6 ◽  
Author(s):  
Angela Voloshina ◽  
Anatolii Panchenko ◽  
Oleg Boltynskiy ◽  
Igor Panchenko ◽  
Olena Titova
Keyword(s):  
Distribution System ◽  
Hydraulic System ◽  
Hydraulic Drive ◽  
Fluid Distribution ◽  
Working Fluid ◽  
Hydraulic Motor ◽  
Hydraulic Motors ◽  
Output Characteristics ◽  
Kinematic Diagram ◽  
The Impact

The output characteristics of a planetary (orbital) hydraulic motor could be significantly improved if the kinematic diagrams for its working fluid distribution system are chosen correctly and substantiated. Fluctuations in the flow of the power fluid cause pulsation in the cavity of the input pressure of the hydraulic motor. This results to vibration of the hydraulic system elements. Thus, the hydraulic motor can be considered as a source of pulsation which leads to functional failures of the hydraulic system. As they run at low rotational speeds with high torque, planetary hydraulic motors are commonly applied for a hydraulic drive in active working tools of self-propelled machinery. It has been established that one of the main components of a planetary hydraulic motor, which causes pressure pulsations, is its distribution system. The frequency and amplitude of these pulsations depends on the kinematic diagram for the distribution system of the power fluid. Therefore, we studied how the kinematic diagram for the distribution system effects on the output characteristics of a planetary motor. Since the change in the capacity of a distribution system with various kinematic diagrams influences on the output characteristics of a planetary motor, the impact was investigated. The kinematic diagrams, which improve the output characteristics of planetary hydraulic motors, were justified. 

Modeling of a New Crank-Less Rotary Heat Engine Concept for Solar Power Utilization

2018 ◽  
Author(s):  
Muhammad I. Rashad ◽  
Hend A. Faiad ◽  
Mahmoud Elzouka
Keyword(s):  
Degrees Of Freedom ◽  
Unit Cost ◽  
Heat Engine ◽  
Structure Design ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Heat Engines ◽  
And Performance ◽  
Engine Concept

This paper presents the operating principle of a novel solar rotary crank-less heat engine. The proposed engine concept uses air as working fluid. The reciprocating motion is converted to a rotary motion by the mean of unbalanced mass and Coriolis effect, instead of a crank shaft. This facilitates the engine scaling and provides several degrees of freedom in terms of structure design and configuration. Unlike classical heat engines (i.e. Stirling), the proposed engine can be fixed to the ground which significantly reduce the generation unit cost. Firstly, the engine’s configuration is illustrated. Then, order analysis for the engine is carried out. The combined dynamics and thermal model is developed using ordinary differential equations which are then numerically solved by Simulink™. The resulting engine thermodynamics cycle is described. It incorporates the common thermodynamics processes (isobaric, isothermal, isochoric processes). Finally, the system behavior and performance are analyzed along with studying the effect of various design parameters on operating conditions such as engine speed, output power and efficiency.

The Dimension Match and Parameters Setting of the Hydraulic Motor for the Hydraulic-Electromagnetic Energy-Regenerative Shock Absorber

2017 ◽  
Author(s):  
Jia Mi ◽  
Lin Xu ◽  
Sijing Guo ◽  
Mohamed A. A. Abdelkareem ◽  
Lingshuai Meng ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Shock Absorber ◽  
High Efficiency ◽  
Mechanical Energy ◽  
Hydraulic Cylinder ◽  
Electromagnetic Energy ◽  
Operating Conditions ◽  
Hydraulic Motor ◽  
Wide Range ◽  
Regenerative Shock Absorber

Hydraulic-electromagnetic Energy-regenerative Shock Absorber (HESA) has been proposed recently, with the purpose of mitigating vibration in vehicle suspensions and recovering vibration energy traditionally dissipated by oil dampers simultaneously. The HESA is composed of hydraulic cylinder, check valves, accumulators, hydraulic motor, generator, pipelines and so on. The energy conversion from hydraulic energy to mechanical energy mainly depends on the hydraulic motor between two accumulators. Hence, the dimension match and parameter settings of hydraulic motor for the HESA are extremely important for efficiency of the whole system. This paper studies the methods and steps for dimension matching and parameter settings of the hydraulic motor in a case of a typical commercial vehicle. To evaluate suspension’s vibration characteristics, experiments on the target tour bus have been done. Simulations are conducted to investigate the effects of the hydraulic motor in different working conditions. The simulation results verify that the methods and steps adopted are accurate over a wide range of operating conditions and also show that appropriate matching and parameter settings of the hydraulic motor attached in the HESA can work with high efficiency and then effectively improving energy conversion efficiency for the whole system. Therefore, the theory of the matching progress can guide the future design of an HESA.

scholarly journals INVESTIGATION OF TRANSITIONAL PROCESSES IN THE ADAPTIVE SYSTEM OF HYDRAULIC DRIVES OF THE MECHANISM FOR CUTTING AND UNLOADING STALK FODDER

2021 ◽  
pp. 107-114 ◽  
Author(s):  
Volodymyr Rutkevych
Keyword(s):  
Adaptive Systems ◽  
Adaptive System ◽  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Slide Valve ◽  
Drive System ◽  
Design Parameters ◽  
Flow Divider ◽  
Competitive Mechanism ◽  
Transitional Processes

The problem of creating an energy-efficient and competitive mechanism for cutting and unloading stalk fodder from trench storage, by developing and justifying the parameters and modes of operation of the adaptive system of hydraulic drives of the mechanism is researched. The principal implementation of the adaptive system of hydraulic drive of the mechanism for cutting and unloading is proposed, in which a spool flow divider is placed between two executive hydraulic motors, which allows to regulate the supply of a U–shaped frame according to the load change which affects the cutting mechanism. The adaptive system of the hydraulic drive of the mechanism allows to stabilize energy consumption for separation of a portion of a stalk fodder under the condition of change and fluctuation of parameters which essentially influence the process of separation and unloading of a stalk fodder from the monolith. The transients in the adaptive systems of hydraulic drives of the mechanism for cutting and unloading of stalk fodder are received and analyzed. As a result of the study, it was found that by changing the operating widths of the slide valve of the separator in the direction of reduction, a significant increase in the responsiveness of the hydraulic drive system of the mechanism for cutting and unloading to the changes in the loading on the cutting apparatus. As a result, the range of the adjustment of the feeding of the hydraulic cylinder of the U–shaped frame, which increases the efficiency of stabilizing the separation process from the monolith of block-portion of stalk fodder with a minimum power of the hydraulic drive system, is substantially expanded. It is noted that the dynamic characteristics of the hydraulic drive of the mechanism for cutting and unloading stalk fodder adaptive to the load are influenced by the design parameters of the spool flow divider which implements feedback. On the basis of the conducted experimental research recommendations on the choice of constructive parameters of the spool flow divider are given.

scholarly journals MATHEMATICAL MODEL OF THE INTERACTION OF THE SCREW WORKING BODIES OF FOREST FIRE GROUND-THROWING MACHINES WITH THE GROUND COVER

2021 ◽  
Vol 11 (1) ◽  
pp. 163-171
Author(s):  
Petr Popikov ◽  
Anton Pozdnyakov
Keyword(s):  
Mathematical Model ◽  
Forest Fire ◽  
Forest Fires ◽  
Hydraulic Drive ◽  
Ground Cover ◽  
Forest Litter ◽  
Working Fluid ◽  
Hydraulic Motor ◽  
Working Bodies ◽  
Fire Ground

The paper provides an overview of research on the working processes of screw working bodies of technological machines. It is noted that at present such important issues in the theory of auger working bodies as the required number of auger turns, the required position of the auger spiral in relation to the center, etc. have not been fully resolved, since the solution of these issues can provide an increased productivity of the tool. A structural and technological scheme of a forest fire machine with multifunctional modules is proposed, which consists of auger working bodies, which can be changed modularly with a screw metal thread for a brush, depending on the area and type of soil, the rotor of the thrower, with the ability to drive the cutters-throwers and auger working bodies both from the power take-off shaft of the tractor, and using a hydraulic motor, a guide casing. A mathematical model of an auger working body with a hydraulic drive has been compiled for removing the ground cover with forest litter when extinguishing forest fires with a ground gun, so that combustible materials do not fall into the fire zone together with the soil flow from the rotor-thrower. The working process of the hydraulic drive of the auger working bodies of a forest fire ground-sweeping machine is described by a system of differential equations, including the equations of translational and rotational movements of the auger working body and the equation of the flow rate of the working fluid. The problem of optimization of kinematic and dynamic parameters of auger working bodies of forest fire ground-sweeping machine is set

scholarly journals Analysis of the Throttle Speed Control Efficiency in Volumetric Hydraulic Drives

2019 ◽  
pp. 13-33
Author(s):  
K. D. Efremova ◽  
V. N. Pilgunov
Keyword(s):  
Control Method ◽  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Movement Speed ◽  
Working Fluid ◽  
Total Efficiency ◽  
Control Methods ◽  
Output Link ◽  
Hydraulic Cylinders ◽  
Load Characteristics

To control a movement speed of the output link of an executive hydraulic engine (hydraulic cylinder or hydraulic motor), volumetric hydraulic drives traditionally use volumetric and throttle control methods. Under volumetric control, a supply unit employs a pressure-regulated positive displacement pump, as a result of which it is impossible or difficult to separate and independently control the movement speed of the output links of the hydraulic cylinders. In case of throttle control, there is a significant dependence of the speed of the output link on the load it overcomes, a low efficiency of the hydraulic drive and hereto related active heating of the working fluid, as well as large energy losses. However, in embodiment, due to lack of an expensive variable pump, this method of control is much cheaper and can be used in a multi-channel hydraulic drive with a centralized supply unit.Depending on the throttling device localization in the hydraulic drive circuit, there are series (primary or secondary control) and parallel (working fluid bypass adjustment) throttle connection schemes. The secondary control scheme, which generates a pressure in the outlet of the executive hydraulic engine, is preferable due to the fact that it provides an increased pressure in both cavities of the executive hydraulic engine and, accordingly, a lack of combined air bubbles in the working fluid. Heat released in the throttle is discharged directly into the tank, and the pressure in the outlet reduces the danger level of the emergency situation consequences in the event of an unauthorized change in the sign of the load to be overcome. The quality of control is, mainly, assessed by the type of load characteristics, i.e. dependences of the output link speed and its developed power on the load to be overcome, as well as by the control efficiency (the total efficiency value of the regulating and executive subsystems of the hydraulic drive). The dependence of the dynamics and kinematics of the hydraulic drive on the control methods are of particular interest.The proposed paper, based on the developed mathematical models and their testing for specific sizes of hydraulic cylinders presents the numerical values of the load characteristics and dependences of the total efficiency on the load value to be overcome. Shows that the speed load characteristic steepness of an executive hydraulic cylinder and the sign of its derivative are determined by the throttle control method. The greatest power developed by the output link of the hydraulic engine is shifted to the loads that are 50 ... 70% of their maximum value.As a result of theoretical studies using numerical calculation methods, a technique has been developed for selecting a throttle control method with an assessment of its quality and efficiency. The results of the conducted studies expand the capabilities to forecast the dynamics and kinematics of the output link of the hydraulic drive at the stage of its engineering design.

CFD Simulation of an Alfa-Stirling Engine to Study the Geometrical Parameters on the Engine Performance

2019 ◽  
Author(s):  
Ana C. Ferreira ◽  
Senhorinha F. C. F. Teixeira ◽  
Ricardo F. Oliveira ◽  
José C. Teixeira
Keyword(s):  
Heat Exchanger ◽  
Power Output ◽  
Cfd Simulation ◽  
Engine Performance ◽  
Stirling Engine ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Cold Temperatures ◽  
Temperature Heat

Abstract An alpha-Stirling configuration was modelled using a Computational Fluid Dynamic (CFD), using ANSYS® software. A Stirling engine is an externally heated engine which has the advantage of working with several heat sources with high efficiencies. The working gas flows between compression and expansion spaces by alternate crossing of, a low-temperature heat exchanger (cooler), a regenerator and a high-temperature heat exchanger (heater). Two pistons positioned at a phase angle of 90 degrees were designed and the heater and cooler were placed on the top of the pistons. The motion of the boundary conditions with displacement was defined through a User Defined Function (UDF) routine, providing the motion for the expansion and compression piston, respectively. In order to define the temperature differential between the engine hot and the cold sources, the walls of the heater and cooler were defined as constant temperatures, whereas the remaining are adiabatic. The objective is to study the thermal behavior of the working fluid considering the piston motion between the hot and cold sources and investigate the effect of operating conditions on engine performance. The influence of regenerator matrix porosity, hot and cold temperatures on the engine performance was investigated through predicting the PV diagram of the engine. The CFD simulation of the thermal engine’s performance provided a Stirling engine with 760W of power output. It was verified that the Stirling engine can be optimized when the best design parameters combination are applied, mostly the regenerator porosity and cylinders volume, which variation directly affect the power output.

scholarly journals Thermal Energy Recovery from a Grid Connected Photovoltaic-Thermal (PVT) System Using Water as Working Fluid

2018 ◽  
Vol 7 (4.36) ◽  
pp. 389
Author(s):  
Alhassan Salami Tijani ◽  
Amer Farhan Bin Md Tahir ◽  
Jeeventh Kubenthiran ◽  
Baljit Singh Bhathal Singh
Keyword(s):  
System Design ◽  
Thermal Efficiency ◽  
Energy Recovery ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Geometrical Configuration ◽  
Ansys Fluent ◽  
Design Concepts ◽  
Pressure Distributions

A Photovoltaic Thermal collector (PVT) is a combination of Photovoltaic (PV) and Thermal (T) collector. Many studies have tried to improve the electrical efficiency and thermal efficiency of this PVT system. The efficiency is influenced by many system design parameters and operating conditions such as the absorber temperature, velocity and pressure distributions. In this study, two new design concepts of absorber configuration of thermal collector have been investigated. This study also provides an important opportunity to advance the understanding of the effect of different geometrical configuration on the performance of the absorber.  Simulations were performed using ANSYS FLUENT 16.0 for both absorbers to determine the best absorber design that gives the highest thermal efficiency. Based on the simulations performed, perpendicular serpentine absorber proved to be the best design with the higher thermal efficiency of 56.45%.    

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