/library/oar/handle/123456789/76397 2025-11-08T10:11:39Z 2025-11-08T10:11:39Z /library/oar/handle/123456789/101458 2022-09-06T07:33:48Z 2015-01-01T00:00:00Z

Title: Thermo-mechanical studies of large hadron collimators in accident scenarios Abstract: The performance of the Large Hadron Collider (LHC) strongly depends on the correct functionality of the LHC collimation system. With a nominal stored beam energy of 362 MJ and a beam momentum of 7 TeV / c, beam accident scenarios must be studied well to assess if the collimator design is robust against possible error scenarios in operation. One of the serious accident scenarios in the LHC is an asynchronous beam dump. While the primary and secondary collimators are designed to withstand such beam impacts, there may be machine conditions that expose the metal-based tertiary collimators (TCTs) and put them at risk of damage. A numerical finite element (FE) model is thus developed in this thesis and applied to investigate the thermo-mechanical response of a TCT in novel jaw error cases derived from an asynchronous beam dump accident. The effectiveness of operating with tilted collimator jaws is identified and it is found that a jaw inclination of -1 mrad can mitigate the damage caused by an accidental beam impact on a TCT. The thermo-mechanical response of TCTs to proton and 208Pb82+ ion beam impacts is also compared and it is concluded that heavy ion operation in the LHC poses no additional challenges on the structural integrity of TCTs during a beam impact. The developed FE model is complemented by the commissioning of thermal and structural characterisation campaigns of the TCT jaw insert material (INERMET® 180) under varying temperature and strain-rate conditions. Moreover, a dedicated beam experiment at the CERN High Radiation to Materials (HiRadMat) facility has successfully validated the reliability of the developed FE model, thus giving confidence in the prediction of damage by such numerical simulations. The work presented in this thesis provides a more thorough understanding of the thermo-mechanical behaviour of TCTs during beam impact in accident scenarios. This is achieved by taking into account all relevant collimator damage limits in a detailed study of various relevant scenarios for the operation of the LHC and its risk optimisation. Description: M.PHIL.

2015-01-01T00:00:00Z /library/oar/handle/123456789/101069 2022-08-26T08:49:15Z 2015-01-01T00:00:00Z

Title: Innovative approaches to solar distillation Abstract: It is estimated that by 2025, two-thirds of the world's population will be living under water-stressed conditions. In many countries, the supply of fresh water from natural resources is already scarce. In such instances energy driven desalination of sea or brackish water is required. People living in remote or disaster areas may lack fresh water as well as energy supplies. A possible solution for such circumstances is renewable desalination which uses renewable energy to desalinate seawater. This study focused on solar stills, the basic constituent of solar desalination technologies. The design of a conventional solar still was modified by replacing the insulated opaque sides with transparent glass. This increased the condensation capacity and when tested under natural weather conditions the productivity was improved by around 43% to 5.5 litres/m2 .day. The improved simple still was used as a benchmark to compare other modified solar still configurations. The sides of the latter stills were also made of glass. In an attempt to create a thin film of water to enhance the evaporation process, a titanium dioxide evaporator was used. When irradiated with ultraviolet radiation, Ti02 exhibits photo-induced hydrophilicity. Two solar stills comprising an inclined evaporator were tested under natural weather conditions simultaneously: one with a Ti02 coating and the other painted black. They both reached the same productivity, however the Ti02 unit operated at a lower temperature due to the lower solar absorptance of Ti02. The improved wettability of titanium dioxide compensated for the lower temperature. However scale formation was observed and it is believed that this attenuated the photo-induced hydrophilic properties. The inclined evaporator stills reached an evaporator efficiency 8 .6% lower than that of the improved simple solar still. A solar chimney and externally water cooled copper condensers were used to improve the convection and condensation processes of a solar still. The buoyant pressure generated by the solar chimney was used to induce a convective current and carry the water vapour from the evaporation chamber to the condensers. This improved the evaporator efficiency by 8.9%. However, since the evaporator area was reduced by 14% to make space for ventilation grilles, the overall production rate was 6.3% lower than that of the improved simple still. The improved simple solar still reached a productivity which compares and exceeds many improvements described in literature. Further improving this gain without making use of latent heat recovery, proved to be difficult. A double effect solar still, incorporating the vertical glass sides, reached a productivity 20% higher than that of the improved simple still. This study can serve as a basis for future research projects attempting to further investigate the use of titanium dioxide and a solar chimney in solar distillation. Description: PhD

2015-01-01T00:00:00Z /library/oar/handle/123456789/97300 2022-06-08T11:24:24Z 1972-01-01T00:00:00Z

Title: Design of open jet supersonic wind tunnel Abstract: The science of wind tunnel testing has grown in the past few decades from secondary importance to a vital position in aircraft development and during this period substantial research has been done in this field. Unfortunately due to the huge cost involved in building and operating the present-day supersonic wind tunnels our two main educational institution namely the Royal University and the Malta College of Arts Science and Technology - not to mention all the Secondary Schools - are deprived of such fascilities due to their limited funds. Considering the above facts the author has tried to design an inexpensive supersonic wind tunnel that can be used for various flow experiments, with the hope that some future student would take up his work and actually construct such a tunnel. With this objective in mind, it was decided that the 'Open-Jet supersonic wind tunnel', where the nozzle blows directly into the atmosphere, will be best suited for our experimental purposes. This type of open-jet wind tunnel is quite economical since it eliminates much costly equipment such as vacuum pumps, vacuum tanks, diffusers etc. [...] Description: B.ENG (HONS)

1972-01-01T00:00:00Z /library/oar/handle/123456789/97192 2022-06-06T12:00:05Z 1983-01-01T00:00:00Z

Title: Liquid-oxygen : project, design and economic evaluation for Malta Drydocks. Abstract: In writing this project report my overriding goal has been to contribute to Management decisions regarding the availability and production of oxygen at Malta Drydocks. It was not the intention to emphasize any nets scientific or engineering principles, but it certainly presented ample opportunity to apply all that which has been absorbed during the whole course. It is true that an economic evaluation is a difficult job that requires long engineering experience and maturity. However I had the advantage of being freshly acquainted with the theory and calculations. This project consists mainly of two parts : a project design and and economic evaluation. Both parts have been dealt with in great detail. The aim of dealing these two aspects in parallel was to show how the fundamentals of engineering design can be blended with engineering economics to produce a final specification; how textbooks para-meters can be applied to the solution of a real problem. It was worth doing such a practical project for the simple reason that I had to tackle problems which were totally unrelated to my past experience and, in some cases I have to admit, quite beyond my capabilities. In fact I have found myself in the harsh industrial world which is no longer dealing with frictionless pulleys and water flowing in clean smooth pipes; instead real problems, such as producing enough oxygen to meet the demand, are the order of the day. No longer is there a unique answer to each problem (as I was accustomed to find at the foot of the tutorial sheet l); indeed there were cases were problems had several solutions and sometimes no answer at all. [...] Description: B.ENG (HONS)

1983-01-01T00:00:00Z