The focus of the present contribution is hydraulic energy recovery by means of hydropneumatic multi-chamber accumulators. A simulation study is presented comparing two different multi-chamber accumulator concepts for energy recovery in an exemplary load case involving a forklift mast. The first concept is based on the “Double Piston Accumulator” /1/. It is compared to the so-called “Digital Accumulator” /2/. Both similarities and differences of the two concepts are discussed in the presentation.

This paper focuses on thermal analysis of a direct driven hydraulic setup (DDH). DDH combines the benefits of electric with hydraulic technology in compact package with high power density, high performance and good controllability. DDH enables for reduction of parasitic losses for better fuel efficiency and lower operating costs. This one-piece housing design delivers system simplicity and lowers both installation and maintenance costs. Advantages of the presented architecture are the reduced hydraulic tubing and the amount of potential leakage points. The prediction of the thermal behavior and its management represents an open challenge for the system as temperature is a determinant parameter in terms of performance, lifespan and safety. Therefore, the electro-hydraulic model of a DDH involving a variable motor speed, fixed-displacement internal gear pump/motors was developed at system level for thermal analysis. In addition, a generic model was proposed for the electric machine, energy losses dependent on velocity, torque and temperature was validated by measurements under various operative conditions. Results of model investigation predict ricing of temperature during lifting cycle, and flattened during lowering in pimp/motor. Conclusions are drawn concerning the DDH thermal behavior.

This paper describes an investigation into the effects of fluid bulk modulus and traction coefficient properties on piston pump flow losses and radial pison motor torque losses through experimentation, modelling and simulation. Synthetic ester, high bulk modulus, multi-grade, and single grade mineral oils were evaluated. The high bulk modulus fluid exhibited 20% lower pump case and compensator flow losses than a conventional mineral oil of the same viscosity grade. Low traction coefficient fluids reduced the lowspeed torque losses of the radial piston motor by 50%. Physical models for pump case flow and motor torque losses were derived from the experimental data. Field data was collected from a hydraulically propelled agricultural machine. This data was used to model fluid performance in the machine. The simulation results predict that at an operating temperature of 80⁰C, optimizing the bulk modulus and traction coefficients of the fluid could reduce flow losses by 18% and torque losses by 5%. These findings demonstrate the potential of combining comprehensive fluid analysis with modeling and simulation to optimize fluids for the efficient transmission of power.

This paper studies a method for active electrohydraulic force compensation in industrial scale high power applications. A valve controlled cylinder moves a mass using the force of inertia to compensate for the reaction forces of an industrial process. Two strategies for force compensation are developed and investigated in a 160 ton clamping unit of an injection moulding machine to significantly reduce the excitation. Results of the different strategies are shown and evaluated. Advantages and drawbacks of the developed electrohydraulic force compensation are discussed.

This paper is presenting the application of Power Regenerative Boom(PRB) system to excavator. In order to increase the fuel efficiency of the excavator, potential energy of the front structure is recuperated by the hydraulic hybrid system with electric-hydraulic control, during boom down motion. Charged energy into accumulator is reused after boom down motion, the pressurized oil goes to hydraulic motor. The hydraulic motor is mounted on the engine PTO(Power Take-Off), therefore output torque of the hydraulic motor assists the diesel engine directy, it leads to decrease fuel consumption of diesel engine. After the system design and simulation investigation, the presented system was installed into Doosan’s 38ton excavator, DX380LC-3 model, and the energy saving result was verified by a digging and dumping repetition test. The test result shows that fuel consumption was dramatically decreased by 5.0 L/hr compared to the standard DX380LC-3.

Nowadays underwater gliders have become to play a vital role in ocean exploration and allow to obtain the valuable information about underwater environment. The traditional approach to the development of such vehicles requires a thorough design of each subsystem and conducting a number of expensive full scale tests for validation the accuracy of connections between these subsystems. However, present requirements to cost-effective development of underwater vehicles need the development of a reliable sampling and testing platform that allows the conducting a preliminary design of components and systems (hardware and software) of the vehicle, its simulation and finally testing and verification of missions. This paper describes the development of the HIL test bench for underwater applications. Paper discuses some advantages of HIL methodology provides a brief overview of buoyancy variation systems. In this paper we focused on hydraulic part of the developed test bench and its architecture, environment and tools. Some obtained results of several buoyancy variation systems testing are described in this paper. These results have allowed us to estimate the most efficient design of the buoyancy variation system. The main contribution of this work is to present a powerful tool for engineers to find hidden errors in underwater gliders development process and to improve the integration between glider’s subsystems by gaining insights into their operation and dynamics.

Complexity management is the key to success for mobile machinery where the variety of customers and applications requires individual solutions. This paper presents the way Bosch Rexroth supports each OEM with hydraulic controls – from specification and conception towards application and production. It gives examples how platforms and processes are optimized according to the customer needs. The demand for flexible, short-term deliveries is met by an agile production with the technologies of Industry 4.0.

Water distribution system utilities must be able to maintain a system’s assets (i.e., pumps, tanks, water mains, etc.) in good working condition in order to provide adequate water quantity and quality to its customers. Various asset management approaches are employed by utilities in order to make optimal decisions regarding the renewal of system components. Part of a good asset management approach is performing a comprehensive risk analysis which consists of considering all potential ways in which the system may fail, the likelihood failure of for each scenario, and the consequences of said failure. This study investigates a water distribution system’s risk of failure due to both acute transient events (e.g., pump trip) and standard pressure fluctuations due to daily system operations. Such an analysis may be useful in optimal decision making such as asset monitoring, scheduling of condition assessments or system renewal projects, policy implementation, and investment priorities in order to keep the utility’s total costs at a minimum. It may also be useful as a precautionary measure to help prevent catastrophic failures such as large main blowouts for which the utility would incur substantial costs, both direct and indirect. As part of this thesis, a database of water distribution system models is used to analyze the effects of an acute transient event for different system configurations. The database was created at the University of Kentucky and has been made available to the research community to test newly developed algorithms for various studies including optimal system operations and optimal system design.

Thesis (MBA)--Stellenbosch University, 2012. / With the advent of shale gas exploration in the Karoo region, the purpose of this study was to investigate the possible socio-economic impacts of shale gas development on the town of Beaufort West in the Karoo. A qualitative study method was used to establish possible socio economic impacts by reviewing literature with regard to existing shale gas development as well as a case study from the United States of America (USA). A desktop study of Beaufort West was carried out to establish current socio economic trends in the town. Semi-structured interviews were conducted with key stakeholders to establish their concerns and opinion regarding the possibility of shale gas exploration and production in the area of Beaufort West in the Karoo. The results of the study concluded that the concerns of the key stakeholders were definitely relevant as their livelihood would be threatened if there was any possibility of contamination of their water sources. Other possible socio economic impacts included infrastructure concerns with regard to road maintenance, tourism declining and the threat of noise and air pollution. The study recommends that if the shale gas development process were to go ahead, the South African government would need to ensure that best practices are incorporated by all gas drilling companies. A team of qualified and trained regulators should monitor well pads and hydraulic fracturing methods as well as volumes of water used and the disposal of waste water. The regulations existing in the country should be revised to incorporate the stringent standards of other countries that have strict monitoring policies in place. In order to protect the people of the Karoo and the heritage of South Africa, the government must ensure that gas companies are held liable for any kind of environmental or socio economic impact.

Increasing urbanization is often accompanied by problematic changes in watershed hydrology. Decreasing surface permeability can lead to increased overland flow volumes, which may spread surficial contaminants and increase the strain on municipal stormwater infrastructure. This study examines a mixed-use property in the Proctor Creek watershed in Atlanta, Georgia, to better understand how land-management practices influence soil overland flow potential. Field saturated hydraulic conductivity (Kfs) measurements were collected from soils 1) subjected to compaction, 2) in urban agricultural use, and 3) under common lawn maintenance. Mean values were 9.1E-7 cm/s, 2.2E-4 cm/s, and 9.0E-6 cm/s respectively. Measurements were collected in-situ with the use of the Aardvark constant-head permeameter. Statistical analyses indicated a substantial difference in Kfs based on land-management practices and that urban farming can increase soil Kfs and limit overland flow. Additional analysis revealed no significant difference in grain-size distributions suggesting land-management practices controlled Kfs, not soil texture.