Dresden, Techn. Univ., Diss., 2004. / Computerdatei im Fernzugriff.

Dresden, Techn. Universiẗat, Diss., 2004.

No description available.

A thesis, submitted to the Faculty of Engineering, University of the Witwa,t(m~~ rand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. -;;., Johannf,'"~l)Urg,. April'25, 1994 / A numerical' and experiruental. investig~tion ~£free~cylinder Stirling engines is repbited. Tllis work evolved from an attempt to de~,elop a palt.icular freecylinder Stirlingengineif::oncept, such that commerci~~lmanufa<:ture and application as .tll~power source for a wateP pu.mp could be. coosidered. Available desigI(~QoIs' 'were not. dirittly applicable .to the engine being ~onsi<:lered. .The linea'f altalysis technique (coupled ~ith segond orderheat tra~sferj,thermody: gamic and "loss ,analysis), dey-eloped and implernented as 18 computer, program~ e by nM Bercho~i~,z was therefore ext~nded to allow the simulation of free-cylinder engines. .The ,s~lut.ipn procedure (follows ~ more, gen~raHzed fqrm than that adopted by Betr~hovvttz.. As a ]."esrutsymbolic manipulation ..and solution of the equations was impracticaL However numericalroot map gen~rat!oIl and ,the simple pr?~uction of force vector ~iagrams q,llr,)ws useful design mformatlon babe obtained: ~0 n .. _ '. '.' .r, ' _ . ". ,' ' _ ' " -'~-::~_, ,; Experimentah~orkwas carried out .on-two very diff,~rent machines. 'A Sufi;' p,ower free-cylinder Stirling ,',engni,e,pr,ototype Jb,Q.elded,disapopi,,ntlllg.•res,u,lts, a~ ,.' '. _'!7.. . ,the engine did, not run: satisfactorily. However the. data gathered provides a useful check of the general applicability of t11-ecouple4 analysis, method. The second engine, a modified S,1lnpowerModel B-lO,Demonstra.~T 'yielded motion and pressure data .over a wide l'al1ge bf operating conditions} The effects o£" \I changes in parameters such as,thl:fcase-ground spring stiffness, di~placer spring stiffness, case mass, charge pressure, Qot-end temperature and load. were explored. Agreement between experlmentalreeults arid simula,tio\l:r~s41ts uS~flg the coupled analysis is reasonable, particularly when one consicI'ersoi;hewid~ range of operatin;g conditions over which the compari§on is made. " , , /.(""" ,0 ,

Ph. D. (Mechanical Engineering), Faculty of Engineering, University of the Witwatersrand, 1986

A resonantly-coupled ��-Stirling (RCAS) cooler was designed and constructed. Tests on air and helium were performed with constant driving displacement over a range of frequencies. The effects of changing driving amplitude and charged pressure were studied. The use of stainless steel bellows in place of pistons eliminated the problem of piston seals and relaxed the construction tolerances. The fatigue life of the bellow is, however, a problem. The experimental optimization based on Taguchi methods was performed on regenerator mass, regenerator wire diameter, vibrating mass, and damping coefficient. Driven by a voice coil actuator, the characteristic phase shift of the Stirling cycle cooler was demonstrated where the hot-end displacement led the cold-end displacement. The 90�� phase shift was selected as the natural frequency. The pressure-volume diagrams for each working space were plotted and the indicated powers were determined. The compression powers in the hot and cold-ends show maximum values near the natural frequency. The mechanisms are different. At the hot-end where the displacement was kept constant, operation near the natural frequency gave a maximum pressure ratio and also maximized the compression power. The phase shifts in the cold-end were, however, relatively constant. The maximum pressure ratio and amplitude gave the maximum expansion power near the natural frequency. The expansion powers in the cold-end as indicators of cooling potential were approximately 2-4 watts for the air case, and 3-7 watts for the helium case. In both air and helium tests, the value of the parasitic losses reached 12 watts. The temperature difference developed across the regenerator is considered an indication of the cooling capacity. Good correlations were found between the indicated cooling capacity in the expansion space and the temperature difference. For a given size of cooler, the use of helium offered higher cooling capacity due to smaller pressure drop loss and smaller amplitude ratio. Higher cooling performance was also attained from helium at elevated pressures. / Graduation date: 1998

Increasing energy demands and environmental problems require innovative systems for electrical and thermal energy production. In this scenario, the development of small scale energy systems has become an interesting alternative to the conventional large scale centralized plants. Among these alternatives, small scale combined heat and power (CHP) plants based on Stirling Engines (SE) have attracted the interest among research and industry due to the potential advantages that offers. These include low maintenance, low noise during operation, a theoretically high electrical efficiency, and principally the fuel flexibility that the system offers. However, actual engine performances present very low electrical efficiencies and consequently few successful prototypes reached commercial maturity at elevated costs.Considering this situation, this thesis presents a numerical thermodynamic study for micro scale CHP-SE systems. The study is divided in two parts: The first part covers the engine analysis; and the second part studies the thermodynamic performance of the overall CHP-SE system. For the engine analysis a detailed thermodynamic model suitable for the simulation of different engine configurations was developed. The model capability to predict the engine performance was validated with experimental data obtained from two different engines: The GPU-3 Stirling engine studied by Lewis Research Centre; and the Genoa engine studied on the experimental rig built at the Energy Department at the Royal Institute of Technology (KTH). The second part of the research complemented the study with the analysis of the overall CHP-SE system. This included numerical simulations of the different CHP components and the sensitivity analysis for selected design parameters.The complete study permitted to assess the different operational and design configurations for the engine and the CHP components. These improvements could be implemented for test field evaluations and thus foster the development of more efficient SE-CHP systems. In addition, the detailed thermodynamic-design methodology for the SE-CHP systems was established and the numerical tool for the design assessment was developed. / <p>QC 20150327</p>

Thesis (M.S.)--Ohio University, November, 1991. / Title from PDF t.p.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 113-114). Also available via the Internet.

To see built form is to see colour. Alternatively, architecture cannot be colourless. Even glass-clad buildings reflect their surroundings while all-white structures are revealed through various shadows and shades. To what degree, then, should colour be considered an architectural element?James Stirling and Architectural Colour, a PhD thesis by Michael William Farr submitted to the University of Manchester in 2013, explores how, exactly, architect James Stirling (1924-92) used colour and what it might say about the evolution of his design ethos. Going beyond what has been written so far this investigation explores the significance of colour in the eclectic array of strikingly individual buildings Stirling designed throughout his career. But while these structures are presented as often visually arresting and idiosyncratic, their varied colour schemes also reveal significant thematic consistencies across his oeuvre. Initially discussion centres on Stirling’s rather contrary use of relatively muted colours. By simply countering expectations or clashing with established contextual characteristics, Stirling ensured his buildings visually attracted attention, courting comment and controversy. In addition it is proposed that he used colour as a means of enticing and inviting those who saw/used his buildings to explore and investigate the very fabric of his structures. As his palette became bolder, so too did his contextual references. Acquainted with the attention-grabbing benefits of incongruous colours, Stirling also recognized the increasing importance of context. By combining sympathetic forms with ever-brighter colour schemes he paradoxically designed buildings that simultaneously fitted in while standing out. It is also argued that these much brighter colours represent a regard for those using his buildings dating back to his and James Gowan’s Preston Housing Project (1957-61). His exploration of structural candour in some projects left them less than hospitable, but the overt anthropocentricity of his later designs is not presented as entirely new. If his colour schemes, in later years, changed considerably, his motivations did not. Focusing on specific design issues - contrariness, structural explication, contextualism and anthropocentricity – this thesis does not attempt classification. Set against Modernism’s demise and Post-Modernism’s ascendancy, Stirling’s relationship to both is explored; his propensity to draw upon any style he felt appropriate revealing the futility of labelling his work as either one or the other. If his earliest designs contain the eclecticism and metaphoric content normally associated with Post-Modern architecture, his later buildings employed a typically Modernist candour regarding materials and techniques. Throughout his career Stirling consistently sought to design buildings that were visually striking, contextually inspired and inviting to explore. His reliance upon both a multiplicity of styles and the considered use of colour was fundamental to these aims.