The automotive industry has been in a marathon of advancement over the past decades. This is partly due to global environmental concerns about increasing amount of air pollutants such as NOx (oxides of nitrogen), CO (carbon monoxide) and particulate matters (PM) and decreasing fossil fuel resources. Recently due to stringent emission regulations such as US EPA (Environmental Protection Agency) and CARB (California Air Resource Board), improvement in fuel economy and reduction in the exhaust gas emissions have become the two major challenges for engine manufacturers. To fulfill the requirements of these regulations, the IC engines including gasoline and diesel engines have experienced significant modifications during the past decades. Incorporating the fully flexible valvetrains in production IC engines is one of the several ways to improve the performance of these engines. The ultimate goal of this PhD thesis is to conduct feasibility study on development of a reliable fully flexible hydraulic valvetrain for automotive engines. Camless valvetrains such as electro-hydraulic, electro-mechanical and electro-pneumatic valve actuators have been developed and extensively studied by several engine component manufacturers and researchers. Unlike conventional camshaft driven systems and cam-based variable valve timing (VVT) techniques, these systems offer valve timings and lift control that are fully independent of crankshaft position and engine speed. These systems are key technical enablers for HCCI, 2/4 stroke-switching gasoline and air hybrid technologies, each of which is a high fuel efficiency technology. Although the flexibility of the camless valvetrains is limitless, they are generally more complex and expensive than cam-based systems and require more study on areas of reliability, fail safety, durability, repeatability and robustness. On the contrary, the cam-based variable valve timing systems are more reliable, durable, repeatable and robust but much less flexible and much more complex in design. In this research work, a new hydraulic variable valve actuation system (VVA) is proposed, designed, prototyped and tested. The proposed system consists of a two rotary spool valves each of which actuated either by a combination of engine crankshaft and a phase shifter or by a variable speed servo-motor. The proposed actuation system offers the same level of flexibility as camless valvetrains while its reliability, repeatability and robustness are comparable with cam driven systems. In this system, the engine valve opening and closing events can be advanced or retarded without any constraint as well as the final valve lift. Transition from regenerative braking or air motor mode to conventional mode in air hybrid engines can be easily realized using the proposed valvetrain. The proposed VVA system, as a stand-alone unit, is modeled, designed, prototyped and successfully tested. The mathematical model of the system is verified by the experimental data and used as a numerical test bench for evaluating the performance of the designed control systems. The system test setup is equipped with valve timing and lift controllers and it is tested to measure repeatability, flexibility and control precision of the valve actuation system. For fast and accurate engine valve lift control, a simplified dynamic model of the system (average model) is derived based on the energy and mass conservation principles. A discrete time sliding mode controller is designed based on the system average model and it is implemented and tested on the experimental setup. To improve the energy efficiency and robustness of the proposed valve actuator, the system design parameters are subjected to an optimization using the genetic algorithm method. Finally, an energy recovery system is proposed, designed and tested to reduce the hydraulic valvetrain power consumption. The presented study is only a small portion of the growing research in this area, and it is hoped that the results obtained here will lead to the realization of a more reliable, repeatable, and flexible engine valve system.

The master´s thesis deals with reconstruction of RCF test rig AXMAT. Main goal is design new hydraulic load system and his realization. The first part of thesis describes similar experimental machines and their pros and cons. This analysis is base for complete reconstruciton of AXMAT. New hydraulic load system allows dynamic programmable load cycles. Control system with close loop and feedback was created in software Matlab – Simulink. Main frame was reconstructed too. Control and action parts were asseble to station. Output of thesis is function sample.

The desire to use more energy efficient heavy equipment in the earth-moving industry has rapidly increased due to higher environmental awareness. Studies within electrification and new types of hydraulic circuit architecture has shown great potential regarding energy savings. The advantages of implementing a closed, pump-controlled, hydraulic system for controlling the boom cylinder on the back-hoe of an articulated backhoe loader is evaluated in this thesis. The possibilities of electric energy regeneration is investigated and to what extent energy savings can be expected for the complete hydraulic system during normal operation. In order for pump-controlled systems to even be conceivable alternatives to conventional valve-controlled system, they must be able to achieve the same characteristics and driveability as the original valve-controlled systems. The possibilities of imitating the characteristics of a valve-controlled hydraulic system with hydro-mechanical pressure feedback is also investigated in this thesis. The original characteristic is able to be imitated with the implemented pump-controlled system with simple means by defining the current characteristic as the relationship between the operator input, cylinder load and cylinder flow. The evaluated sectioned hydraulic system demonstrates energy savings of 30% during both a light and a heavy duty cycle. With components more suitable for this type of system and an improved control strategy, energy savings of over 50% compared to the original system is believed to be possible.

In accident analysis regarding nuclear power plants, it is very common to use thermal hydraulic system codes, such as TRACE, developed by U.S. NRC. In the case of licensing a power plant, this is one of the necessities. TRACE is a relatively new thermal hydraulic system code and a lot of knowledge is needed to implement it in a correct way, especially in accident analysis, where it is a requirement that the rules and statements in Appendix-K, dealing with criteria for ECCS-models, are modelled. In this thesis an improved model of a Swedish Boiling Water Reactor within TRACE is realized and tested. Afterwards, once a working and representative model has been obtained, a sensitivity study in conducted in order to investigate the sensitivity of TRACE for a couple of thermal hydraulic parameters. The sensitivity study is focussing on the eect of the peak cladding temperature, as well as the coolability of the nuclear fuel in terms of quenching and quench-front velocities. It is found to be hard to say unilaterally what the eect of changing a certain number of parameters on the reactor behaviour is. As it turns out to be, although strongly related, the peak cladding temperatures and the quench phenomena can behave dierently

A significant part of the environmental impact of a heat pump isgenerally related to the direct emission of the refrigerant fluid during thelife time of the machine. Although the Montreal Protocol has alreadylargely secured its status as a success story by cutting the ozone deplentationrefrigerants drastically, we still have to deal with the challengesresulting from climate change.Natural refrigerants such as Propane permits to design more ecofriendlysystem without sacrificing the performance of the machine. Thethesis work is part of a European project called Next Generation of HeatPumps working with Natural fluids (NxtHPG) whose primary aim is thedevelopment of heat pumps working with Natural refrigerant that aresafe, reliable, with high efficiency and high capacity. Royal Institute oftechnology (KTH) is one of the partner of the project and responsiblefor the experimental campaign of two large propane heat pumps: an airsource heat pump (Case 1 ) and a ground source heat pump suitablefor boreholes (Case 2 ). Few cases in literature report on studies aboutlarge capacity heat pumps using propane as refrigerant.This thesis project focuses on the experimental evaluation of theCase 2 from an energy point view. The safety issues about the use of flammable refrigerant, i.e propane, are briefly reported; however theyare not considered strictly part of the thesis work since they are coveredin other phases of NxtHPG project. Experimental tests for Case 1 werenot conducted during this thesis work because of delays in the prototypedelivery from the manufacturer. However, concerns about the hydraulicloop of the test rig of both the heat pumps was identified and a newdesign was suggested and implemented.During the experimental campaign for Case 2 a significant numberof tests were performed according to a specific text matrix definedfrom the EN 14285 standard. A simple heat pump model has beenused to evaluate the overall performance of the machine from the directmeasurements. The heat pump components (compressors, condenser,evaporator, expansion valve) have been analysed in details by definingspecific analysis model for each one. The results have been comparedwith the manufacture expectation.The prototypes demonstrated to have potentially very good performance,since in the first set of tests the machine behaved as expectedby the IMST-ART software. On the other hand, a drop of the unitefficiency and capacity have been registered during the experimentalcampaign for similar working condition. Two different explanations areinvestigated to clarify the strange phenomenon. The first hypothesisconsiders minor internal damage in the compressor, as check valve leakage;consequence of the use of the compressor in a tandem layout. Itgenerates a back-flow in the non working compressor. The second explanationregards inert gas infiltration in the system. On the otherhand they are not able to explain entirely the system issues and theyneed to be confirmed by the manufacturer analysis of the open compressor.The further improvements, proposed and discussed with themanufacture companies involved, can help to solve the question markson the strange system behaviour during the future work. The nextexperimental campaign for Case 1 that will start on April 2015.The software IMST-ART, used to predict the performance of theheat pump, is demonstrated to be a fast and useful tool. The model ofthe software for propane as refrigerant and brazed plate heat exchangerpredicts adequately the experimental measurement. / Una parte significativa dell’impatto ambientale relativo a una pompadi calore è legato alle emissioni dirette di refrigerante durante ilperiodo di vita della macchina. Nonostante l’accordo di Montreal siagià stato considerato come un successo storico per il drastico taglio deirefrigeranti dannosi per lo strato di ozono, bisogna ancora fronteggiarele sfide relative al cambiamento climatico.Refrigeranti naturali, come il Propano, permettono di realizzaremacchine più ambientalmente compatibili senza però sacrificare le prestazionidella macchina stessa. Questo lavoro di tesi fa parte di unprogetto Europeo chiamato Next Generation of Heat Pumps workingwith Natural fluids (NxtHPG), in cui obiettivo primario è quello di svilupparepompe di calore che lavorano con fluidi Naturali che allo stessotempo siano sicure, affidabili, con elevata efficienza e taglia.Royal Institute of technology (KTH) è uno dei partner del progettoe anche responsabile della campagna sperimentale di due pompe dicalore a propano di grossa taglia: una pompa ad aria Case 1 e unageotermicaCase 2. Sono pochi gli esempi in letteratura che riguardanolo studio di macchine di questo tipo di grande taglia, questo costituiscela novità del lavoro.Il lavoro di tesi presentato è incentrato principalmente sulla valutazionesperimentale da un punto di vista energetico di Case 2. Leproblematiche legate alla sicurezza legate all’utilizzo di refrigeranti infiammabili,quale è il propano, sono solo citate; d’altra parte non sonoconsiderate strettamente facenti parte del lavoro di tesi in quando altrefasi del progetto NxtHPG sono incentrate su questo argomento.Misure sperimentali per Case 1 non sono state condotte durante illavoro di tesi a causa di ritardi nella consegna dei prototipi da parte dell’aziendaproduttrice. Ad ogni modo sono stati individuate problematichelegate ai circuiti idraulici dell’installazione sperimentale di entrambele pompe di calore e successivamente risolte con l’implementazione diuna nuova proposta di circuito idraulico.Durante la campagna sperimentale di Case 2, sono stati svolti undiscreto numero di misurazioni secondo una ben specifica test matrixderivata dalla normativa europea EN 14285. Un semplice modello dipompa di calore è stato utilizzato per la valutazione delle prestazionigenerali della macchina a partire dalle misurazioni dirette. I componenti della pompa di calore, quali compressore, condensatore, evaporatore,valvola di espansione, sono state analizzati separatamente definendouno specifico modello per ognuno di essi e comparato con i risultatiattesi dai produttori.Il prototipo di Case 2 dimostra avere ottime potenzialità come prestazioni,in quanto, durante il primo set di test, il comportamento dellamacchina era in linea con le previsioni del software IMST-ART. D’altraparte, durante la campagna sperimentale, si è evidenziato un fortecalo delle prestazioni nonostante le condizioni di funzionamento fosseropressoché simili. Per spiegare questa anomalia, due differenti ipotesisono state formulate. La prima assume la presenza di di deterioramentiminori nel compressore, come perdite nella valvola di non ritorno (checkvalve), conseguente ad l’utilizzo in configurazione tandem. Si genererebbeun flusso riverso di refrigerante nel compressore non funzionante.La seconda ipotesi riguarda infiltrazione di gas inerte all’interno dellamacchina. D’altra parte tali ipotesi non sono in grado di spiegareinteramente le problematicità nel sistema e hanno necessità di essereconfermate dall’analisi a compressore aperto da parte della aziendaproduttrice.Successivi perfezionamento dei prototipi sono stati proposti e discussicon le aziende produttrici coinvolte, e questo permetterebbe dirispondere ai punti di domanda riguardo lo strano comportamento delsistema. La prossima campagna sperimentale per Case 2 inizierà adAprile 2015. Il software IMST-ART, usato per predire le performancedella pompa di calore, ha dimostrato essere uno strumento veloce e utile.Il modello implementato nel software per il propano e per gli scambiatoridi calore a piatti predice adeguatamente le misure sperimentali. / Next Generation of Heat Pumps working with Natural fluids (NxtHPG)

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The aviation environment holds challenging application constraints for efficient hydraulic system noise reduction devices. Besides strong limits on component weight and size, high safety and reliability standards demand simple solutions. Hence, basic silencers like inline expansion chambers and Helmholtz-Resonators are state-of-the-art aboard commercial aircrafts. Unfortunately, they do not meet today’s noise attenuation aims regarding passenger comfort and equipment durability. Significant attenuation performance is expected from active concepts that generate anti-phase noise. However, such concepts remain a long term approach unless related costs, e.g. due to additional power allocation and real-time control equipment can be avoided. In this paper an active fluid borne noise attenuation concept is discussed that accounts for the mentioned constraints. An aircraft hydraulic pump is considered as main noise source. The active attenuator is an in-house rotary valve design. The basic feature is a known direct shaft coupling principle of pump and rotary valve, so no speed/ frequency control of the valve and no separate power supply are required. The common-shaft principle is further simplified here and proposed as integral feature of future “smart pumps”.

<p>The electrification trend affecting off-road vehicles is paving the way toward dedicated electrified hydraulic actuation systems. Although traditional centralized fluid power architectures are still utilized in many applications for low cost, power density, and reliability, nowadays emission policy results in an increasing interest in developing electro-hydraulic actuator (EHA) solutions. EHAs enable non-throttling actuation and energy recuperation during overrunning loads, leading to higher transmission efficiency and lower fuel consumption. These features in energy efficiency make EHAs competitive in meeting emission regulations compared to conventional hydraulic solutions.</p> <p>The key challenge in developing the EHA solution comes from the high cost and space requirements, especially for the adoption of self-contained EHAs in mobile applications. In this study, two architectures for the EHA are proposed, a closed-circuit architecture and an open-circuit one, to determine the most practical and efficient configuration. The most effective open-circuit architecture with distributed concepts is further investigated for implementation, which requires less modification of the mechanical structures and performs more efficiently than the closed-circuit alternative. The proposed EHA is driven by an electro-hydraulic unit (EHU) consisting of a variable-speed electric motor and a fixed-displacement hydraulic pump, which is relatively cost-effective. A novel hydraulic configuration is proposed, which allows the EHA to cover full-speed operating ranges in four quadrants. </p> <p>To verify the EHA design, the behavior of the proposed system should be predicted prior to costly experiments and demonstrations. For this purpose, an integrated simulation model is developed based on the lumped parameter approach in the Amesim environment. The model includes the electric system, the hydraulic system, and the mechanism to be implemented, which are capable of flexible analysis of functionality, efficiency, and thermal performance.</p> <p>In this work, a dedicated test rig for EHA testing is developed. The test rig can help verify EHA performance, test the control algorithm, and diagnose errors before implementing the system on real applications. The experimental results from the test rig also validate the simulation model. An independent load drive of the test rig allows testing all possible  loading conditions of the proposed EHA, thus demonstrating the energy performance in four quadrants. Thermal behavior is investigated with long duty cycles to determine the need for additional cooling equipment. After the validation of the hydraulic configuration, a power electronics setup is added to the test rig, which allows to drive the EHA system with the novel designed EHUs. Validation on the test platform paves the way for implementation in a vehicle. </p> <p>As a final step, the proposed EHA system is implemented in a reference vehicle, a Case New Holland TV380 skid steer loader. A novel designed EHU is adopted to drive the system for technology demonstration. The energy savings capacity of the EHA is investigated in comparison to the baseline measurements of the traditional open-center hydraulic architecture. The impressive savings from the reduction of throttling losses and energy recovery guide the possible commercialization of such EHAs in mobile hydraulic applications. The controller design of the implemented EHA system is investigated with the aim of improving the dynamic performance, e.g., reducing damping oscillation. Basic power management strategies are also studied to integrate EHA with the power train of current hydraulic machines. Regarding future work, based on this research but not within the scope of this study, the proposed EHA system can be adopted with different types of prime movers, such as axial piston machines as the hydraulic part of an EHU. Furthermore, the design approach proposed in this study can help resize the EHA system for other applications with different loading conditions and power requirements, and the energy savings capability can be further investigated. With this, a comprehensive market analysis will be performed for the commercialization of EHA. </p>

Indiana University-Purdue University Indianapolis (IUPUI) / The harvested energy of wind can be transferred to the generators either through a gearbox or through an intermediate medium such as hydraulic fluids. In this method, high-pressure hydraulic fluids are utilized to collect the energy of single or multiple wind turbines and transfer it to a central generation unit. In this unit, the mechanical energy of the hydraulic fluid is transformed into electric energy. The prime mover of hydraulic energy transfer unit, the wind turbine, experiences the intermittent characteristics of wind. This energy variation imposes fluctuations on generator outputs and drifts their angular velocity from desired frequencies. Nonlinearities exist in hydraulic wind power transfer and are originated from discrete elements such as check valves, proportional and directional valves, and leakage factors of hydraulic pumps and motors. A thorough understanding of hydraulic wind energy transfer system requires mathematical expression of the system. This can also be used to analyze, design, and predict the behavior of large-scale hydraulic-interconnected wind power plants. This thesis introduces the mathematical modeling and controls of the hydraulic wind energy transfer system. The obtained models of hydraulic energy transfer system are experimentally validated with the results from a prototype. This research is classified into three categories. 1) A complete mathematical model of the hydraulic energy transfer system is illustrated in both ordinary differential equations and state-space representation. 2) An experimental prototype of the energy transfer system is built and used to study the behavior of the system in different operating configurations, and 3) Controllers are designed to address the problems associated with the wind speed fluctuation and reference angular velocity tracking. The mathematical models of hydraulic energy transfer system are also validated with the simulation results from a SimHydraulics Toolbox of MATLAB/Simulink®. The models are also compared with the experimental data from the system prototype. The models provided in this thesis do consider the improved assessment of the hydraulic system operation and efficiency analysis for industrial level wind power application.

The high price of batteries in working machines with electric drives offer a potential for investment in energy-saving hydraulic systems. The decentralized power network opens up new approaches for hydraulic- and hybrid circuits. In addition, the regeneration of energy can be used at any point of the machine. For the example of an excavator arm drive with a double cylinder two compact hydraulic circuits are presented, which relieve a central hydraulic system.