Start-stop systems are widely used in the car industry today but have not yet been fully implemented in the heavy-duty vehicle industry. The greater loads arising in the engines leads to excessive wear of the hydrodynamic bearings during starts and stops which has a distinct impact on the machine´s lifetime performance and reliability. This master thesis involves a comparative study of how different surface topographies of a shaft affects hydrodynamic bearing wear during start and stop conditions. The objective was to see if one can extend the bearing lifetime by doing minor changes to the shaft surface. This has been done by redesigning an existing start-stop test rig, increasing its operating system oil temperature to 90°C to provide a more accurate description of the bearing environment, to be able to conduct a series of start-stop cycling experiments. Upon examination of the experiment results, it becomes clear that a more polished surface of the shaft does reduce bearing wear significantly during starts and stops. It was also noticed that a more polished shaft surface does reach full-film lubrication at a lower rotational speed of the shaft, separating the shaft and the bearing surfaces. / Start-stoppsystem används idag i stor utsträckning inom bilindustrin men har ännu inte blivit implementerat fullt ut i den tunga fordonsindustrin. De större belastningarna som uppstår i motorn leder till överdrivet slitage på de hydrodynamiska glidlagren under start och stopp och har en tydlig inverkan på maskinens livslängd och pålitlighet. Detta examensarbete har innefattat en jämförande studie om hur olika axelytor påverkar nötningen av hydrodynamiska glidlager vid start och stoppförhållanden. Målet var att se ifall man kan lyckas förlänga lagrets livslängd genom att genomföra mindre förändringar av axelytan. Detta har utförts genom att omkonstruera en befintlig start-stopprigg, ökat oljesystemets driftstemperatur till 90°C för att ge en mer exakt beskrivning av den riktiga lagermiljön, för att sedan ha utfört en serie start och stopp experiment. Resultaten från experimenten visade tydligt att en mer polerad axelyta minskar lagerslitningen avsevärt under start och stopp. Det noterades också att en mer polerad axelyta ger fullfilmssörjning vid en lägre axelrotationshastighet, varvid axeln och lagerytorna separeras.

M.Tech. (Architectural Technology) / It is estimated that commercial buildings are responsible for 5.4% of worldwide Green House Gas (GHG) emissions through their construction and on-going operation. In developed countries this figure can go up to 30%. The environmental control industry is one of the large consumers of this energy. Heating, ventilation and air conditioning (HVAC) contribute approximately 15% of South Africa's current peak electrical demand consumption according to Eskom (the South African electricity utility). The purpose of this dissertation is to analyse and evaluate methods to reduce the energy consumption of the HVAC system in a commercial office building. This encompasses careful building design to reduce heat loads and promote the circulation of fresh air; the use of energy-efficient air-conditioning systems and the incorporation of materials and technology to reduce energy consumption. This will be based upon a case study of the new SANRAL (South African National Roads Agency Limited) head office building in Val-DeGrace, Pretoria. A deductive research approach will be followed. The as-designed Actual Building is modelled with the appropriate energy modelling software and its annual energy usage is obtained. A benchmark based Notional Building complying with SANS 204:2008 criteria of the same size, shape, location and operational schedules as the Actual Building is also modelled and its energy usage results compared to that of the Actual Building. This comparison will determine how energy efficient the Actual Building's HVAC system is compared to a conventional Notional Building. Quantitative data collection is performed by empirical measurement of the energy usage of the as-built Actual Building. The raw data (power usageofthe HVAC system) is measured by Schneider Electric PM9c™ power meters located in the HVAC distribution boards of the building. This raw data are collected by Schneider Electric's ION Enterprise' power management software which has a user friendly interface from where the data can be downloaded. The power management software is connected to an ANDOVEWM Building Management System (BMS). Due to commissioning procedures and the timeframe at hand for the completion of this dissertation measurements could only be taken over a 7 month period. Operational data were measured from July 2011 to March 2012 thus accounting for summer, winter and a seasonal changeover period. The modelled energy usage results of the as-designed Actual Building are compared to the measured energy usage data obtained from the as-built Actual Building. This comparison serves to evaluate the accuracy of the software model...

This thesis details a study of strategies used to limit the flow generated noise encountered in the outlet diffusers of high velocity heating, ventilation and air conditioning (HVAC) duct systems. The underlying noise rating criterion is drawn from the specifications covering ocean going aluminium fast ferries. Although directed primarily towards the fast ferry industry the results presented herein are applicable to other niche high velocity HVAC applications. Experimental tests have been conducted to prove the viability of a high velocity HVAC duct system in meeting airflow requirements whilst maintaining acceptable passenger cabin noise levels. A 50 mm diameter circular jet of air was expanded using a primary conical diffuser with a variety of secondary outlet configurations. Noise measurements were taken across a velocity range of 15 to 60 m/s. An optimum outlet design has been experimentally identified by varying the diffuser angle, outlet duct length and the termination grill. A 4 to 5 fold reduction in required duct area was achieved with the use of a distribution velocity of 20 to 30 ms-1, without exceeding the prescribed passenger cabin noise criteria. The geometric configuration of the diffuser outlet assembly was found to have a pronounced effect on the noise spectrum radiating from the duct outlet. The development of a numerical model capable of predicting the flow induced noise generated by airflow exiting a ventilation duct is also documented. The model employs a Large Eddy Simulation (LES) CFD model to calculate the turbulent flow field through the duct diffuser section and outlet. The flow-generated noise is then calculated using a far field acoustic postprocessor based on the Ffowcs-Williams and Hawkings integral based formulation of Lighthill???s acoustic analogy. Time varying flow field variables are used to calculate the fluctuating noise sources located at the duct outlet and the resulting far field sound pressure levels. This result is then used to calculate the corresponding far field sound intensity and sound power levels. The numerical acoustic model has been verified and validated against the measured experimental results for multiple outlet diffuser configurations.

This thesis details a study of strategies used to limit the flow generated noise encountered in the outlet diffusers of high velocity heating, ventilation and air conditioning (HVAC) duct systems. The underlying noise rating criterion is drawn from the specifications covering ocean going aluminium fast ferries. Although directed primarily towards the fast ferry industry the results presented herein are applicable to other niche high velocity HVAC applications. Experimental tests have been conducted to prove the viability of a high velocity HVAC duct system in meeting airflow requirements whilst maintaining acceptable passenger cabin noise levels. A 50 mm diameter circular jet of air was expanded using a primary conical diffuser with a variety of secondary outlet configurations. Noise measurements were taken across a velocity range of 15 to 60 m/s. An optimum outlet design has been experimentally identified by varying the diffuser angle, outlet duct length and the termination grill. A 4 to 5 fold reduction in required duct area was achieved with the use of a distribution velocity of 20 to 30 ms-1, without exceeding the prescribed passenger cabin noise criteria. The geometric configuration of the diffuser outlet assembly was found to have a pronounced effect on the noise spectrum radiating from the duct outlet. The development of a numerical model capable of predicting the flow induced noise generated by airflow exiting a ventilation duct is also documented. The model employs a Large Eddy Simulation (LES) CFD model to calculate the turbulent flow field through the duct diffuser section and outlet. The flow-generated noise is then calculated using a far field acoustic postprocessor based on the Ffowcs-Williams and Hawkings integral based formulation of Lighthill???s acoustic analogy. Time varying flow field variables are used to calculate the fluctuating noise sources located at the duct outlet and the resulting far field sound pressure levels. This result is then used to calculate the corresponding far field sound intensity and sound power levels. The numerical acoustic model has been verified and validated against the measured experimental results for multiple outlet diffuser configurations.

The main goal of the diploma thesis is to design a new ventilation and heating system in an old house after its reconstruction. The design also includes consideration of the possibility of using renewable resources. A central heat recovery ventilation systém is designed to ensure ventilation of the building. The heating design is based on two independent heat sources. It is a wood boiler and a gas condensing boiler. After considering renewable sources, a photovoltaic system is designed. The results of individual calculations and drawing documentation of designs are also attached.

Процесс проектирования систем отопления сопровождается большим количеством временных затрат, вызванных как расчетами, так и построением большого количества элементов в пространстве модели. Создание дополнительных программных модулей позволяет проектировщиком больше внимания уделять принятию принципиальных решений и тратить меньше времени на выполнение циклически повторяющихся однотипных действий, тем самым ускоряя процесс создания проекта. В ходе данной диссертационной работы был выполнен аналитический обзор методов создания программных модулей, а также был разработан и реализован скрипт по построению теплого пола для компании «Строительное проектирование «КУБ». / The process of heating systems designis accompanied by a large amount of time caused by both calculations and the construction of a large number of elements in model space. Creating additional software modules allows the designer to pay more attention to making fundamental decisions and spend less time performing cyclically repeated actions of the same type, thereby speeding up the process of creating a project. In the course of this dissertation work, an analytical review of methods for creating software modules was carried out, and a script for building a warm floor for the Construction Design KUB company was developed and implemented.