I have decided to deal with the issue of "Risk Sources of Ammonia Cooling Systems and Their Eventual Accidental Impacts" as the risk of leakage from the cooling systems using ammonia as a coolant still prevails these days. Eventual accidental leakage simulation models were applied to several winter stadiums using ammonia as a coolant. Based on these results, it has been assessed how dangerous these sources for the citizens living in their surroundings are and measures to increase safety were suggested, too.

Made available in DSpace on 2014-10-09T12:27:28Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:47Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho foram desenvolvidos calculos neutrônicos, termo-hidráulicos e de segurança para avaliar a seguranca operacional de um dispositivo de irradiação a ser colocado no núcleo do reator IEA-R1 do IPEN-CNEN/SP. Este dispositivo de irradiação é utilizado para alojar miniplacas de combustvel do tipo dispers~ao de U3O8-Al e U3Si2-Al, com 19,75% em peso de 235U e densidades, respectivamente, de ate 3,2 gU/cm3 e 4,8 gU/cm3. Estas miniplacas serão irradiadas a queimas acima de 50% do 235U, de forma a qualificar este tipo de dispersão para utilização no Reator Multipropósito Brasileiro (RMB), em concepção. Para os calculos neutrônicos, foram utilizados os programas computacionais 2DB e CITATION. O programa FLOW foi utilizado para determinar o fluxo de refrigerante no irradiador, permitindo o cálculo das temperaturas máximas atingidas nas miniplacas de combustível com o programa MTRCR-IEA-R1. Um Acidente de Perda de Refrigerante (APR) foi analisado com os programas computacionais LOSS e TEMPLOCA, permitindo o cálculo das temperaturas nas miniplacas de combustível após o esvaziamento da piscina do reator. Os cálculos demonstraram que a irradiação deverá ocorrer sem consequências adversas no núcleo de reator IEA-R1. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:08/55686-6

Les opérations de maintenance des routes en conditions hivernales sur réseaux routiers constituent un enjeu important pour maintenir l’offre de mobilité en situation dégradée. Elles génèrent des coûts d’exploitation directs et indirects élevés, liés en particulier à l’utilisation intensive de fondants routiers. Par ailleurs, leur impact environnemental doit être pris en considération. Nous étudions ici une structure de chaussée non soumise à ce type d’astreinte, grâce à la présence d’une couche de liaison drainante dans laquelle circule un fluide chaud, permettant ainsi d’éviter le dépôt de neige ou la formation de glace en surface. Dans le cadre d’une démarche en faveur de l’emploi d’énergie renouvelable, un tel dispositif pourrait permettre de récupérer l’énergie thermique disponible en surface de chaussée en période chaude, de l’acheminer vers un lieu de stockage (ex : géothermie) et de l’utiliser en période froide. Nous étudions ici la fonction d’échangeur de chaleur entre le fluide et la chaussée, la fonction de stockage externe à la chaussée n’étant pas abordée hormis dans la revue bibliographique. La structure de chaussée considérée comporte trois couches d’enrobés. La couche de roulement et la couche de base sont constituées de matériaux classiquement utilisés dans les chaussées, à base de liants hydrocarbonés. Le matériau de la couche de liaison possède une porosité supérieure à 20%. La structure de chaussée est supposée avoir un dévers de l’ordre de 2%. Une chaussée expérimentale instrumentée a été mise en oeuvre pour recueillir des grandeurs thermo-physiques de la chaussée. Un modèle thermo-hydrique 2D est d2veloppé numériquement pour calculer la distribution de température dans le corps de chaussée lorsque l’on injecte un fluide à température d’entrée donnée, en haut de dévers. Les paramètres du modèle sont identifiés à partir des données expérimentales recueillies sous diverses sollicitations climatiques. On analyse dans un premier temps la sensibilité de la distribution de température en surface de chaussée aux différents paramètres du modèle (conductivité hydraulique, dévers, conductivités thermiques, chaleurs massiques), afin d’optimiser les procédures nécessaires au contrôle sous contraintes de températures positives en tout point. Dans une deuxième partie, des données expérimentales recueillies durant une période estivale d’un mois ont servi à valider le modèle thermique 1D. Une maquette de laboratoire a également permis d’identifier des paramètres en milieu saturé et non saturé. La dernière partie de thèse est consacrée au calcul des quantités énergétiques récupérables pendant la période estivale à l’aide des données de la réglEmentation thermique RT2012. Elles sont comparées aux quantités énergétiques de chauffage nécessaires pendant la période hivernale en s’appuyant sur des données de la RT2012 et des données de la Direction Interdépartementale des Routes Massif (DIR MC) ; l’objectif final étant de déterminer les performances énergétiques du système. / Winter maintenance operations for road networks are an important issue for maintaining the mobility in degraded situations, but generate high direct and indirect exploitation costs, particularly related to the intensive use of road de-icing and environmental impact. We study a road structure free of this penalty, thanks to a bonding drainage asphalt layer, circulated by a hot fluid, to prevent the deposition of snow or ice formation on the road surface. As part of an integrated vision of promoting the use of renewable energy, such device could be used to recuperate the thermal energy available in the road surface during the hot period, to transport it to a storage location (e.g. geothermal) and use it during cold period. We study here the heat exchanger function between the fluid and the road, the external storage function to the road being not addressed. The considered pavement structure has three asphalt layers.The bearing layer and the base layer are formed of conventional materials with hydrocarbon-based binders. The material of the bonding layer has a porosity of 20% and based on the use of a binder resistant to a prolonged circulation of the coolant. The road structure is assumed to have a slope of about 2 to 3%. An instrumented experimental road is implemented to collect data on the thermo-hydraulic response of the pavement structure. A thermo-hydraulic 2D model is designed to simulate the temperature field in the road structure when the fluid is injected at the upslope side of the road with a target temperature. This model is calibrated from experimental data collected on the experimental road subjected to meteorological solicitations. Initially, the sensibility of the distribution of the surface temperature of the road toward various model parameters (hydraulic conductivity, transversal slope, thermal conductivities, heat capacities) is analysed, in order to study the optimization of control procedures allowing to keep positive the road surface temperature at any point (e.g. determination of the minimum fluid injection temperature, under given meteorological data). In a second time, pavement thermal parameters is identified using control optimal method in order to validated unidimensionnel thermal model applied on July experimental data. In third time, hydraulic model is validated experimentaly using a laboratory mockup in saturated and unsaturated conditions. In a fourth time, thermo-hydraulic bidimensionnal model is validated numerically using mesured data of experimental pavement. Finally, harvest energy in summer period using thermal reglementation RT2012 data and heating energy in winter period using RT2012 and Massif Interdepartmental Road Direction (DIR MC) are calculated in order to evaluate system performance.

Developments regarding internal cooling techniques have allowed the operation of modern gas turbine engines at turbine inlet temperatures which exceed the metallurgical capability of the turbine blade. This has allowed the operation of engines at a higher thermal efficiency and lower specific fuel consumption. Modern turbine blade-cooling techniques rely on external film cooling to protect the outer surface of the blade from the hot gas path and internal cooling to remove thermal energy from the blade. Optimization of coolant performance and blade-life estimation require knowledge regarding the influence of cooling application on the blade inner and outer surface heat transfer. The following study describes a combined experimental and computational study of heat transfer augmentation near the entrance to a film-cooling hole. Steady-state heat transfer results were acquired by using a transient measurement technique in an 80 x actual rectangular channel, representing an internal cooling channel of a turbine blade. Platinum thin-film gauges were used to measure the inner surface heat transfer augmentation as a result of thermal boundary layer renewal and impingement near the entrance of a film-cooling hole. Measurements were taken at various suction ratios, extraction angles and wall temperature ratios with a main duct Reynolds number of 25×103. A numerical technique, based on the resolution of the unsteady conduction equation, using a Crank-Nicholson scheme, was used to obtain the surface heat flux from the measured surface temperature history. Computational data was generated with the use of a commercial CFD solver. / Dissertation (MEng)--University of Pretoria, 2008. / Mechanical and Aeronautical Engineering / unrestricted

This thesis is concerned with cutting farm machine and it consists of three parts. Theoretical part describes mechanism of chip formation, shape of the chips, temperature of the chips, technological variables describing chips, chip conveyor, chip crusher, briquetting press and coolant filter. In the next part there is proposal of design of cutting farm machine for production cell consists of six machining center. At last part there is design proposal and calculation of chip conveyor.

The test facility ROCOM (Rossendorf Coolant Mixing Model) has been built for the investigation of coolant mixing processes in the reactor pressure vessel of pressurised water reactors (PWR). ROCOM is a 1:5 model of the German PWR KONVOI and has been designed for a wide range of different mixing scenarios. ROCOM disposes of four loops with fully controllable coolant pumps. The test facility is operated with demineralised water. For the investigation of mixing, tracer solution (water labelled with salt) is injected into the facility. The transient distribution of the electrical conductivity is is measured at different positions of the flow path by means of wire-mesh sensor technique with high resolution in space and time. The measured conductivity is transformed into a dimensionless mixing scalar. The mixing at quasi-stationary conditions (constant loop mass flow rates) has been investigated in the presented experiments. That concerned nominal operation conditions, the operation with a reduced number of loops and the investigation of cold-water transients with running pumps and conditions of developed natural circulation. In special experimental series, the reproducibility of the results at identicla boundary conditions within the confidence intervalls has been shown. Further, the influence of various factors on the mixing has been investigated. This included the pressure losses at the core bottom plate, the global coolant flow level and the influence of the loop flow rate on the perturbed sector at the core inlet. An analysis of the measurement error of the used measurement technique completes the report.

Heat generated in a machining process is a common and critical obstacle faced in today's machining industries. The heat generated in the cutting zone has a direct negative influence on the tool life which, in turn contributes to increase the manufacturing costs. Especially, in machining of Heat Resistant Super Alloys, HRSA this is a very limiting factor. HRSA are capable of retaining their mechanical strength and hardness at elevated temperatures. This property is advantageous in the application in e.g. aero-engines but also a disadvantage, since it also lowers the machinability significantly. This work is an attempt to improve the heat transfer from the cutting zone, which would lead to an increase in the tool life. To achieve this goal, the cutting tool has been modified to create an improved interface between the coolant and tool in the high-temperature areas. Two generations of inserts have been designed and investigated. Firstly, an insert with surface texture features has been created with the purpose of increasing the available surface area for heat dissipation: First generation, Gen I. Secondly, a GenII was designed as a further improvement of Gen I. Here, several channel features on the rake face were added, reaching out from the contact zone to the near proximity of the cutting edge. This with the purpose of improving access of the coolant closer to the cutting edge. The experiments were conducted in facing operations of Alloy 718 with uncoated round carbide inserts. All experiments were carried out with high-pressure coolant assistance, with a pressure of 16 MPa on the rake face and 8 MPa on the flankface, respectively.The two generations of inserts, Gen I and Gen II, were experimentally evaluated by tool wear analysis in comparison with a regular insert. The results shows that the tool life increased significantly for the Gen I insert, compared to a catastrophic failure of the regular insert at the same conditions. Regarding the Gen II insert,an increase in tool life by approximately 30 to 40 percent compared to Gen I insert was observed.

The automotive industry is currently traversing through the electrification wave. Numerous manufacturers are directing focus to electrify their lineup and reduce emissions. In the frontier of heavy duty diesel trucks, electrification of auxiliary units remains an unexplored potential. An optimized cooling system functioning in sync with a controllable electric coolant pump attempts to reduce parasitic losses and emissions. The cooling flow requirements in challenging conditions may also be fulfilled. Although electric coolant pumps are found increasingly in passenger cars, the implication of independently operating them in a heavy duty diesel truck is an important objective to be explored. The purpose of this project is to generate different cooling system layouts coupled with electrical coolant pumps. The performance of these layouts is compared with the volume flows in a standard cooling system. Refined layouts which fulfill the cooling system requirements are chosen for verification. 1-D Simulation is used to correlate and verify the trends of the test rig data. The results show an adequate gain in the total volume flow across distinct layouts with the electric coolant pumps. However, numerous challenges are required to be overcome. / Bilindustrin befinner sig mitt i en våg av elektrifiering. Flertalet tillverkare fokuserar på att elektrifiera sitt produktutbud och att minska utsläppen. Inom forskningen kring tunga transporter med dieseldrivna lastbilar, är elektrifiering av kylsystemet ett outforskat område. Ett optimerat kylsystem som är reglerbart med en elektrisk kylvätskepump skulle potentiellt kunna minska energiförluster och utsläpp. Kravet på flödet av kylvätska vid utmanande driftsfall skulle också kunna bli bättre uppfyllda än för dagens system. Trots att det blir allt vanligare att personbilar har elektriska kylvätskepumpar, så har det inte utforskats vad det innebär att ha reglerbara elektriska kylvätskepumpar i dieseldriva lastbilar. Därför är detta ett viktigt område att utforska. Målet med detta projekt är att skapa olika kylsystemskoncept, där den elektriska kylvätskepumpen är en systemkomponent. Prestandan hos dessa principlösningar jämförs sedan med volymflödet i ett standard kylvätskesystem. Koncept som uppfyller kraven för kylvätskesystemet kommer att bli utvalda för vidare verifiering. 1-D simuleringar används för att hitta samband och verifiera mot trenderna som hittas i resultat från en testrigg. Resultaten visar en förbättring i det totala volymflödet för flera av lösningarna, som har en elektrisk kylvätskepump. Men det finns fortfarande flera utmaningar som behöver övervinnas.

The military vehicle, Pansarterrängbil 203 (PATGB 203) demonstrates a fault. There are some components in a coolant circuit that fail due to corrosion while others are unaffected. One of the affected components that will be investigated in this report is the water heater. The subject of this technical investigation has been an issue for FMV, Swedish Defence Materiel Administration since a decade. While seeking out the cause of the coolant circuit failing, this investigation aim to analyzing the underlying problems considering material, factors of corrosion and organization. In order to establish the origin of material and appearance of corrosion, experiments were performed. The experiments showed that the original material is an Al-Si alloy. The micrographs indicated varying stratification of the corrosion throughout the unit. The corrosive deposits consisted mainly of oxygen, silicon, aluminum and sodium. Consequently, the protecting passive oxide layer is compromised, which results in a direct connection between the coolant and the underlying material. This direct connection gives rise to the development of corrosion in the material. Clear underlying causes of the corrosion were not found but the most probable suggest on galvanic corrosion accelerated by a stray current. Properly grounding the components decreases the stray current in the system and is essential to avoid corrosion. If grounding the components is not sufficient, additional checks of the coolant with attention to the pH-value and the function of corrosion inhibitors may indicate corrosion at an earlier stage.

This diploma work is engaged in replacement of gasket main dividing plane of reactor coolant pumps in nuclear power plant Paks. Of the newly suggested gasket is kammprofile gasket with expanded graphite layer. This work contain suggestion and calculation of new sealing a knot and calculation existing sealing the knot. Results are confrontacion and sequentially is discussed influence on main dividing plane HCČ 317 by use the new and the existing gasket. In this work is contained description brief of legislation. This legislation must keep by design components dedicated for nuclear equipment. Next this work contain view of the most important sealing knots used in primary system of Nuclear Power Plant type VVER 440.