A numerical and experimental study on energy saving solutions for mobile hydraulic machinery

Energy saving in mobile hydraulic machinery, aimed to fuel consumption reduction, has been one of the principal interests of many researchers and OEMs in the last years. Many different solutions have been proposed and investigated in the literature in order to improve the fuel efficiency, from novel system architectures and strategies to control the system to hybrid solutions. This thesis deals with the energy analysis of a hydraulic system of a middle size excavator through mathematical tools. In order to conduct the analyses the multibody mathematical model of the hydraulic excavator under investigation will be developed and validated on the basis of experimental activities, both on test bench and on the field. The analyses will be carried out considering the typical working cycles of the excavators defined by the JCMAS standard. The simulations results will be analysed and discussed in detail in order to define different solutions for the energy saving in LS hydraulic systems. Among the proposed energy saving solutions, energy recovery systems seem to be very promising for fuel consumption reduction in mobile machinery. In this thesis a novel energy recovery system architecture will be proposed and described in detail. Its dimensioning procedure takes advantage of the dynamic programming algorithm and a prototype will be realized and tested on the excavator under investigation. Finally the energy saving proposed solutions will be compared referring to the standard machinery architecture and a novel hybrid excavator with an energy saving up to 11% will be presented.

Kinetic and hydraulic studies in high-rate biological filters

Most published work on either low- or high-rate biological filters covers one of three topics: kinetics, microbiology/ecology or hydraulics. These areas have been re-examined together for high-rate filters in order to further integrate them and enable appropriate utilization of low-rate filter experience.

Facility closure management:the case of Vauxhall Motors Luton

Purpose – The purpose of the paper is to present the findings of a study of factory closure management. It details the sequence and the results of the key strategic manufacturing management decisions made from the time of the announcement of the plant closure to the cessation of operations. The paper also includes an analysis of the human resource management (HRM) actions taken during this same time period and their consequences upon all those involved in the closure management process. Design/methodology/approach – The case study methodology consisted of two initial site visits to monitor closure management effectiveness (adherence to plan and the types and frequency of closure management communications). During these visits, documentary evidence of the impact of the closure decision upon production performance was also collected (manufacturing output and quality performance data). Following plant closure, interviews were held with senior business, production and HRM managers and production personnel. A total of 12 interviews were carried out. Findings – The case study findings have informed the development of a conceptual model of facility closure management. Information obtained from the interviews suggests that the facility closure management process consists of five key management activities. The unexpected announcement of a factory closure can cause behavioural changes similar to those of bereavement, particularly by those employees who are its survivors. In addition, similar reactions to the closure announcement may be displayed by those who choose to remain employed by the factory owner throughout the phased closure of the plant. Originality/value – Facility closure management is an insufficiently researched strategic operations management activity. This paper details a recommended procedure for its management. A conceptual model has also been developed to illustrate the links between the key facility closure management tasks and the range of employee changes of behaviour that can be induced by their execution.

Using simulation for facility design: a case study

A discrete event simulation model was developed and used to estimate the storage area required for a proposed overseas textile manufacturing facility. It was found that the simulation was able to achieve this because of its ability to both store attribute values and to show queuing levels at an individual product level. It was also found that the process of undertaking the simulation project initiated useful discussions regarding the operation of the facility. Discrete event simulation is shown to be much more than an exercise in quantitative analysis of results and an important task of the simulation project manager is to initiate a debate among decision makers regarding the assumptions of how the system operates.

Optimization of facility location-allocation problem in customer-driven supply chain

This paper develops and applies an integrated multiple criteria decision making approach to optimize the facility location-allocation problem in the contemporary customer-driven supply chain. Unlike the traditional optimization techniques, the proposed approach, combining the analytic hierarchy process (AHP) and the goal programming (GP) model, considers both quantitative and qualitative factors, and also aims at maximizing the benefits of deliverer and customers. In the integrated approach, the AHP is used first to determine the relative importance weightings or priorities of alternative locations with respect to both deliverer oriented and customer oriented criteria. Then, the GP model, incorporating the constraints of system, resource, and AHP priority is formulated to select the best locations for setting up the warehouses without exceeding the limited available resources. In this paper, a real case study is used to demonstrate how the integrated approach can be applied to deal with the facility location-allocation problem, and it is proved that the integrated approach outperforms the traditional costbased approach.

The design and engineering of a reactor test facility for thermal processing of biomass

This thesis describes the design and engineering of a pressurised biomass gasification test facility. A detailed examination of the major elements within the plant has been undertaken in relation to specification of equipment, evaluation of options and final construction. The retrospective project assessment was developed from consideration of relevant literature and theoretical principles. The literature review includes a discussion on legislation and applicable design codes. From this analysis, each of the necessary equipment units was reviewed and important design decisions and procedures highlighted and explored. Particular emphasis was placed on examination of the stringent demands of the ASME VIII design codes. The inter-relationship of functional units was investigated and areas of deficiency, such as biomass feeders and gas cleaning, have been commented upon. Finally, plant costing was summarized in relation to the plant design and proposed experimental programme. The main conclusion drawn from the study is that pressurised gasification of biomass is far more difficult and expensive to support than atmospheric gasification. A number of recommendations have been made regarding future work in this area.

Multi-function controllers for a hydraulic pump

This project has been undertaken for Hamworthy Hydraulics Limited. Its objective was to design and develop a controller package for a variable displacement, hydraulic pump for use mainly on mobile earth moving machinery. A survey was undertaken of control options used in practice and from this a design specification was formulated, the successful implementation of which would give Hamworthy an advantage over its competitors. Two different modes for the controller were envisaged. One consisted of using conventional hydro-mechanics and the other was based upon a microprocessor. To meet short term customer prototype requirements the first section of work was the realisation of the hydro-mechanical system. Mathematical models were made to evaluate controller stability and hence aid their design. The final package met the requirements of the specification and a single version could operate all sizes of variable displacement pumps in the Hamworthy range. The choice of controller options and combinations totalled twenty-four. The hydro-mechanical controller was complex and it was realised that a micro-processor system would allow all options to be implemented with just one design of hardware, thus greatly simplifying production. The final section of this project was to determine whether such a design was feasible. This entailed finding cheap, reliable transducers, using mathematical models to predict electro-hydraulic interface stability, testing such interfaces and finally incorporating a micro-processor in an interactive control loop. The study revealed that such a system was technically possible but it would cost 60% more than its hydro-mechanical counterpart. It was therefore concluded that, in the short term, for the markets considered, the hydro-mechanical design was the better solution. Regarding the micro-processor system the final conclusion was that, because the relative costs of the two systems are decreasing, the electro-hydraulic controller will gradually become more attractive and therefore Hamworthy should continue with its development.