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We are at a time when energy efficiency and the reduction in the use of non-renewable energy is an important objective in all aspects and will continue to be so, therefore it is necessary to try to reduce energy and heat losses in the systems used in homes and, in particular, in the domestic hot water (DHW) system. This study aims to find out the advantages and disadvantages of an innovative pipe-in-pipe (PIP) system for DHW circulation with respect to the conventional system of two separate pipes. Previous studies have shown that DHW circulation is indeed an important point of energy losses in the home and that it is possible to reduce these losses by using the innovative system under study. The properties and coefficients defining the heat transfer system have been obtained for both the traditional and innovative systems by using empirical equations and iterative processes, indicating a 32% reduction in heat losses in favour of the pipe-in-pipe system. However, this result has been obtained in a kind of case study, using some simplifying assumptions, needed to accomplish to work within limited time. So the result could vary if a somewhat different system is studied, which is why it is necessary to carry out further studies and research on this subject in order optimize DHW systems in buildings.

In this thesis, a stacked double-layer flat plate oscillating heat pipe charged with degassed DI water was designed, fabricated and characterized under different operating conditions (orientation, system or cooling water temperature and heat load). The oscillating heat pipe was designed to dissipate 500 W within a footprint of 170 x 100 mm2. The oscillating heat pipe had a total of 46 channels (23 channels per layer) with a nominal diameter of 2 mm. Tests were performed to characterize the performance of the oscillating heat pipe for (i) axial heat transfer and (ii) as a heat spreader. The stacked oscillating heat pipe showed a distinctive feature in that it overcame the absence of the gravity effect when operated in a horizontal orientation. The thermal performance was found to be greatly dependent on the operational parameters. The oscillating heat pipe was able to dissipate a heat load greater than 500 W without any indication of dry-out. An increase in the cooling water temperature enhanced the performance and was accompanied with an increase in the on/off oscillation ratio. The lowest thermal resistance of 0.06 K/W was achieved at 500 W with a 50℃ cooling water temperature, with a corresponding evaporator heat transfer coefficient of 0.78 W/cm2K. The oscillating heat pipe improved the heat spreading capability when locally heated at the middle and end locations. The thermal performance was enhanced by 27 percent and 21 percent, respectively, when compared to a plain heat spreader. / Thesis / Master of Applied Science (MASc)

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No description available.

The world is continually changing towards more energy efficient alternatives and less pollution. For the traction market, electric powertrains have become the go-to method, superior to both steam and diesel-electric hybrid systems. For subways and trams the natural development now is towards smaller motors with high power output, the goal is to use as much space as possible for the passengers and keep the performance of a larger motor setup. One problem with increasing the power density of the motors is that the accumulated heat from losses also increases per volume. All motors have different efficiency and different limits on temperatures in different parts. For this project a closed, self-ventilated traction motor with axis height 250mm (CSV250) was evaluated. The motor has an input power just above 140kW and the identified limiting factor is the temperature of the bearings, specifically the front bearing located at the fan side of the motor.   An already existing and partly validated ANSYS MotorCAD model was used for full system overview and as a guide to build a COMSOL Multiphysics model of the motor rotor. The COMSOL model could be effectively changed to represent different configurations of the solution. The COMSOL solver is based on the finite element method, FEM, whereas the MotorCAD model is built as a thermal network with lumped parameter method, LPM.    The proposed solution to the high temperature is implementation of heat-pipes in strategic positions. This project only contains evaluation of heat-pipes positioned in the center of the shaft deployed in three different configurations: a short heat-pipe transferring heat from the bearing to the fan, a long heat-pipe transferring heat from the active rotor parts to the fan and a long heat-pipe similar to previous case but with the heat-pipe insulted at the bearing section. The simulations yield performance specifications for the solution design that will give the expected result, complemented with theory this can then give the full appliable solution to the specified problem.   For the short heat-pipe case a decrease in temperature form 116.5 to 96.5°C was achieved in the front bearing by increasing the heat-transfer from the bearing towards the fan with 84.4W. This is well under the preferred temperature of maximum 110°C. In the long heat-pipe case a total of 360W was dispersed through the fan and this lowered the highest temperature point in the rotor from 172.2 to 160.8°C but with the negative effect of increasing the temperature of the front bearing. In the third case the insulation of the long heat-pipe in the bearing section managed to lower this increased temperature from 130.4 to 122.4°C while 360W were still transferred through to the fan. This is under the absolute maximum at 130°C but over 110°C. The results point towards the possibility to increase power density and keeping temperatures manageable using heat-pipes but further work and experiments is needed to prov the concept.

Over the last few years, several advancements have been made in water and wastewater pipe renewal technologies that have allowed utilities to utilize innovative renewal techniques that decrease project costs, the impact of the project on the surrounding citizens and environment, and allow for expedited pipeline renewals compared to traditional open trench methods. The challenge now is in getting utilities to implement new innovative technologies within their system. This thesis provides background information on a number of the technologies available for the renewal of water and wastewater system pipelines. It then provides State of the Art Literature and State of the Art Practice Reviews based on technology use trends in literature and technology use trends in utility practice. The information from both reviews is then synthesized to provide a clear view of the state of the water and wastewater pipeline renewal technology industry, including the trends by pipe material, drivers for renewal, and technology type. / Master of Science

Water plays a critical role in every aspect of civilization: agriculture, industry, economy, environment, recreation, transportation, culture, and health. Much of America's drinking water and wastewater infrastructure; however, is old and deteriorating. A crisis looms as demands on these systems increase. The costs associated with renewal of these aging systems are staggering. There is a critical disconnect between the methodological remedies for infrastructure renewal problems and the current sequential or isolated manner of renewal analysis and execution. This points to the need for a holistic systems perspective to address the renewal problem. Therefore, new tools are needed to provide support for wastewater infrastructure decisions. Such decisions are necessary to sustain economic growth, environmental quality, and improved societal benefits. Accurate prediction of wastewater pipe structural and functional deterioration plays an essential role in asset management and capital improvement planning. The key to implementing an asset management strategy is a comprehensive understanding of asset condition, performance, and risk profile. The primary objective of this research is therefore to develop protocols and methods for evaluating the wastewater pipe performance. This research presents the life cycle of wastewater pipeline identifying the causes of pipe failure in different phases including design, manufacture, construction, operation and maintenance, and repair/rehabilitation/replacement. Various modes and mechanisms of pipe failure in wastewater pipes were identified for different pipe material which completed with results from extensive literature reviews, and interviews with utilities and pipe associations. After reviewing all relevant reports and utility databases, a set of standard pipe parameter list (data structure) and a pipe data collection methodology were developed. These parameters includes physical/structural, operational/functional, environmental and other parameters, for not only the pipe, but also the entire pipe system. This research presents a development of a performance index for wastewater pipes. The performance index evaluates each parameter and combines them mathematically through a weighted summation and a fuzzy inference system that reflects the importance of the various factors. The performance index were evaluated based on artificial data and field data to ensure that the index could be implemented to real scenarios. Developing a performance index led to the development of a probabilistic performance prediction model for wastewater pipes. A framework would enable effective and systematic wastewater pipe performance evaluation and prediction in asset management programs. / Ph. D.

Yes / The performance of buried rigid pipes underneath geogrid-reinforced soil while applying incrementally increased cyclic loading was assessed using a fully instrumented laboratory rig. The influence of varying two parameters of practical importance was investigated; the pipe burial depth and the number of geogrid-layers. Measurements were taken for pipe deformation, footing settlement, strain in pipe and reinforcing layers, and pressure/soil stress on the pipe crown during various stages of cyclic loading. The research outcomes demonstrated a rapid increase in the rate of deformation of the pipe and the footing, and the rate of generated strain in the pipe and the geogrid-layers during the first 300 cycles. While applying further cycles, those rates were significantly decreased. Increasing the pipe burial depth and number of geogrid-layers resulted in reductions in the footing and the pipe deformations, the pressure on pipe crown, and the pipe strains. Redistribution of stresses, due to the inclusion of reinforcing layers, formed a confined zone surrounding the pipe providing it with additional lateral support. The pipe invert experienced a rebound, which was found to be dependent on pressure around the pipe and the degree of densification of the bedding layer. Data for strains measured in the geogrid-layers showed that despite the applied loading value and the pipe burial depth, the tensile strain in the lower geogrid-layer was usually higher than that measured in the upper layer.

Natural Hazards are a risk to buried gas pipeline infrastructure, but these risks are difficult to assess and quantify. This can often lead to the risks not being properly identified by pipeline owners. The risk to pipelines within landslide areas are particularly difficult to assess given the complex nature of landslide movements and the soil-pipeline interaction mechanisms imposing loads on a pipeline. This thesis research examines the relationship between ground movements and strains/stresses in buried pipelines through field measured ground movements and in-situ measured pipe strains/stresses. The pipe stresses and strains are then used to estimate probability of pipeline failure and risk based on RBDA limit states approaches. Within Manitoba Hydro’s pipeline network, three at-risk landslide areas (riverbank and deep river valleys) were selected for detailed studies. A field investigation and monitoring program was undertaken to assess possible sources of load and stresses on pipelines. Soil, ground, and pipe instrumentation were installed at the sites and monitored over a four year period. Monitoring results identified soil near the pipeline does not freeze, and ground movements at valley sites are slow moving (<50 mm/year) landslides. The monitoring results also showed pipe stresses and behaviour were affected by backfilling, changes in river levels, thermal affects, soil-pipe relaxation, and ground movements. Pipe push tests were conducted in conjunction with FEM modelling to examine pipe adhesion and to possible explain the pipe behaviour observed. Several ultimate and serviceability limit states pipe failure modes were assessed using the measured pipe stresses. Statistical analysis was undertaken to calculate the probability of pipeline failure for the various limit states failure modes and compared against limit states targets for several scenarios (backfill loads, initial stress-state of the pipeline, other pipelines within Manitoba Hydro network). Overall, the probability of failure estimates were generally insignificant or low due to a postulated soil-pipe relaxation mechanism which is causing a repeated release in longitudinal pipe stresses as the landslide continues to accumulate ongoing ground movements. Three mechanisms are presented and discussed. The statistical analysis indicate pipelines within Manitoba Hydro’s network may exceed limit states targets for yielding and local buckling depending on the loading scenario and the class of the pipeline within the landslide area. The outcome of the research was used to develop a risk managements system to examine geotechnical hazards within Manitoba Hydro’s pipeline network. Specifically, risks associated with ground movements along natural slopes and at river crossings are examined within the system. / October 2016