Thesis--Finland Institute of Technology. / Bibliography: p. [104]-105.

Solar chimney is an important passive design strategy to maximize solar gain to enhance buoyancy effect for achieving adequate air flow rate and a desired level of thermal comfort inside a building. Therefore, solar chimney has the potential advantages over mechanical ventilation systems in terms of energy requirement, economic and environmental benefits. The main aim of this project is to study the technical feasibility of a solar chimney incorporating latent heat storage (LHS) system for domestic heating and cooling applications. The research work carried out and reported in this thesis includes: the development of a detailed theoretical model to calculate the phase change material (PCM) mass for solar chimney under specific climatic condition, the development of a CFD model to optimise the channel depth and the inlet and outlet sizes for the solar chimney geometry, experimental and numerical investigations of the thermal performance of the proposed system using a prototype set-up, a parametric study on the proposed system to identify significant parameters that affect the system performance was carried out by using the verified numerical model. The numerical and experimental study showed that the numerical model has the ability to calculate the PCM mass for the proposed system for the given weather conditions. The optimum PCM should be selected on the basis of its melting temperature, rather than its other properties such as latent heat. The experimental work on the thermal performance of the proposed system has been carried out. The results indicated that the LHS based solar chimney is technically viable. The outlet air temperature and the air flow rate varied within a small range during phase change transition period which are important for a solar air heating system. A numerical model was developed to reproduce the experimental conditions in terms of closed mode and open mode. The model results were in a close agreement with the experimental results particularly the simulated results for the discharging process. With the verified model, a comprehensive parametric analysis intended to optimise the thermal performance of proposed the system was performed. The results analysed are quantified in terms of charging/discharging time of the PCM, temperature difference between outlet air and inlet air of the solar chimney, and mass flow rate of the chimney, which are the most important quantities of the proposed system.

Within the UK, space heating accounts for 66% of the total domestic energy used. New heating controls may offer a means to reduce this figure and help meet the UK s target of reducing its greenhouse gas emissions by 2050. However these technologies will only save energy if occupants are able to use them effectively. Currently, little is known about how occupants interact with their heating systems, in particular how they use the heating within their home and the reasons behind why it is used a specific way. To investigate further, this thesis presents research which used both qualitative and quantitative methods over two separate studies to uncover why and how households heat their homes and how people use their heating system following the installation of new heating controls. The results identify key drivers which impact how people heat their homes and highlight numerous issues preventing them from using their heating how they wish to. A taxonomy of heating use is presented based on the factors influencing heating use in homes and how those factors impact the use and control of the heating system. Occupants use of new heating controls over a ten month period is presented. Manual interaction with controls is separated from programmed heating schedules showing increased manual use over winter and a reliance on heating schedules during shoulder months. The analysis of measured heating use showed similar findings to larger scale studies, however the demanded set-point temperatures were varied and occupants regularly changed heating schedules throughout winter, indicating some of this complexity may be lost by studies inferring heating use patterns from internal temperature measurements alone. The research presented within this thesis is novel, in developing heating characters based on the factors which influence occupants heating behaviours, by presenting measured heating use, which included measured set-point temperatures, heating schedules and heating use duration. The thesis also presented the complexity of heating use within homes uncovered through use of mixed methods.

<p>The present environmental concerns and the rising human requirement for solutions with better comfort and lower costs have resulted in an increased awareness for the energy use in the built environment. Technical advances in building structural systems and materials, heating and other comfort-providing systems and controlling strategies all lead to the integration of building technology with the function of buildings and the aesthetics. Therefore, in the process of improving the performance of energy systems and increasing the energy efficiency, integrated system approaches are of high importance. Performing the necessary energy analysis before any construction-installation occurs can help designers and decision makers reach guided solutions. Hence, a broad range of calculation tools for evaluating the operation of energy systems and the controls in buildings have been developed the latest years with different levels of complexity and angles of focus.</p><p>However, research and development regarding holistic energy system designs and techniques are in their infancy. The standard tactic has been to isolate system parts, study them as stand-alone sub-systems and focus on optimising components or processes of a complex function. In the present study, it is demonstrated the necessity for uniting energy engineers, architects, installers and technicians regarding decision making upon the energy use for heating, ventilation and air-conditioning (HVAC) in the built environment. Systems approach has been employed for studying the research issue that is presented in the current thesis. An extended part of this treatise has been devoted to systems thinking in practice.</p><p>The thesis demonstrates systematic methods of modelling and analysing certain, integrated, domestic, HVAC applications. The reference system boundaries enclose the building as a construction and as a dynamic function, a comfort-providing system based on a heat pump, a low-temperature hydronic heat distribution system and controls in a residential application. Obviously, these are not the only components met in a hydronic heating system. Numerous pieces of equipment, as piping, circulating pumps, expansion tanks, zone valves, relief valves and other essential elements are needed to make a safe and functional heating system. However, this study focuses on the analysis of the chosen reference system. Several models have been developed in the computational tools of TRNSYS and EES. These tools have been employed because they allow co-solving, hence the integrated system as well as the interaction between the different parts of the system can be studied.</p><p>The foremost result of this study is that approaching the system as a whole provides a better picture of the operation of every system component and the interaction between them. Explanations are given for the parameters that have a significant impact on the system’s performance. The thesis shows the importance of factors that are not easy to predict, as well as the difference in the building’s behaviour under fast changing thermal loads when the incorporated thermal mass is altered. Finally, implementing sophisticated controls for reducing the energy costs without compromising thermal comfort is vital.</p>

The present environmental concerns and the rising human requirement for solutions with better comfort and lower costs have resulted in an increased awareness for the energy use in the built environment. Technical advances in building structural systems and materials, heating and other comfort-providing systems and controlling strategies all lead to the integration of building technology with the function of buildings and the aesthetics. Therefore, in the process of improving the performance of energy systems and increasing the energy efficiency, integrated system approaches are of high importance. Performing the necessary energy analysis before any construction-installation occurs can help designers and decision makers reach guided solutions. Hence, a broad range of calculation tools for evaluating the operation of energy systems and the controls in buildings have been developed the latest years with different levels of complexity and angles of focus. However, research and development regarding holistic energy system designs and techniques are in their infancy. The standard tactic has been to isolate system parts, study them as stand-alone sub-systems and focus on optimising components or processes of a complex function. In the present study, it is demonstrated the necessity for uniting energy engineers, architects, installers and technicians regarding decision making upon the energy use for heating, ventilation and air-conditioning (HVAC) in the built environment. Systems approach has been employed for studying the research issue that is presented in the current thesis. An extended part of this treatise has been devoted to systems thinking in practice. The thesis demonstrates systematic methods of modelling and analysing certain, integrated, domestic, HVAC applications. The reference system boundaries enclose the building as a construction and as a dynamic function, a comfort-providing system based on a heat pump, a low-temperature hydronic heat distribution system and controls in a residential application. Obviously, these are not the only components met in a hydronic heating system. Numerous pieces of equipment, as piping, circulating pumps, expansion tanks, zone valves, relief valves and other essential elements are needed to make a safe and functional heating system. However, this study focuses on the analysis of the chosen reference system. Several models have been developed in the computational tools of TRNSYS and EES. These tools have been employed because they allow co-solving, hence the integrated system as well as the interaction between the different parts of the system can be studied. The foremost result of this study is that approaching the system as a whole provides a better picture of the operation of every system component and the interaction between them. Explanations are given for the parameters that have a significant impact on the system’s performance. The thesis shows the importance of factors that are not easy to predict, as well as the difference in the building’s behaviour under fast changing thermal loads when the incorporated thermal mass is altered. Finally, implementing sophisticated controls for reducing the energy costs without compromising thermal comfort is vital. / QC 20101008

La problématique des émissions de particules fines, posant des risques sanitaires et environnementaux avérés, a été très médiatisée ces dernières années. La solution mise en place consiste à aider financièrement les particuliers pour renouveler le parc d’appareils. Or, une utilisation non optimisée d’un appareil dégrade de manière significative ses émissions. Afin d’amender entre autres cette réflexion, de nombreuses campagnes expérimentales ont été menées au travers de caractérisations physico-chimiques complètes et innovantes des fumées, en particulier des particules fines : la Microscopie Electronique à Balayage, la microanalyse X et la détermination du type de carbone constitutif (Carbone Elémentaire, Carbone Organique). En premier lieu, la définition des paramètres d’utilisation de l’appareil et leurs niveaux de réponse ont permis de proposer une réduction significative des émissions dont celles de particules fines. Ainsi, les impacts des paramètres comme la nature du combustible, le mode d’allumage et l’injection d’air secondaire ont été quantifiés. Ensuite, les mécanismes de formations des particules ont été définis. Dans un second temps, ce travail de thèse s’est intéressé à l’évolution des caractéristiques des particules entre la chambre de combustion de l’appareil et le champ proche, permettant d’aller au-delà de l’étude normative classique. De nouveaux savoirs sur les particules ont ainsi été mis en évidence. L’ensemble de ces nouvelles connaissances, aidant à mieux connaître les particules produites par la combustion de bois dans des appareils indépendants, permettront dans le futur de créer des systèmes de traitement spécifiques et efficaces / The issue of the emissions of fine particles, known for their health and environmental hazards, has been significantly covered in recent years. The governments made the decision to help mainly financially the private individuals in order to renew the domestic appliances stock. However, a non-optimized use of an energy-efficient appliance can degrade system performances. In order to solve this issue, many experimental campaigns have been achieved through complete and innovative physicochemical characterizations of the smoke, especially of the fine particles : Scanning Electron Microscope, X-ray microanalysis and assessment of the constitutive Carbon (Elemental Carbon, Organic Carbon). First of all, the definition of the use parameters for the appliance and their impacts allowed offering a significant reduction of the fine particles emissions. In this work, the influences of the parameters such as the nature of the fuel, the ignition mode and the air secondary injection were in this way quantified. In order to better understand the origin of these emissions produced regardless of the combustion quality, the mechanisms of formation of all kinds of particles were defined. In a second phase, this work paid attention to the evolution of the characteristics of particles from the combustion room to the near-field. This enabled to go over the classic normative study. New knowledge on particles was brought to light, helping to better know the particles generation from domestic wood appliances. This could allow in the future to create some specific and efficient treatment systems

With development within district heating leading to more incorporation of decentralized production, lowered temperature levels are required to enable these possibilities. Therefore, this study was conducted in collaboration with Fortum with the purpose of investigating and quantifying the effects of lowered delivery temperatures on mass flow and return temperatures. When these effects had been determined, the limiting factors were identified as well as the adjustments needed to enable the lowering delivery temperatures. This study is divided into two sections: a modeling of four type buildings and two case studies of specific areas of the Stockholm district-heating grid. The two sections of the study both use an Excel constructed model to examine the effects of the new proposed delivery temperature levels. The first section uses four type buildings with varying internal temperature levels to display how different secondary systems react to the changes in delivery temperature. The second section contains two case studies of outer parts of the grid where actual buildings are modeled. In the case studies the pipes speeds and secondary systems are analyzed to determine limiting factors for the lowering of the delivery temperatures. Overall this study contributes with quantified results of the effects of four lowered delivery temperature profiles on different customer systems. Analysis of the delivery temperatures showed that the largest change was shifting from the actual delivery temperatures of 2011 to the delivery profile that Fortum currently promised to deliver. The pipes of the studied areas were found not to be a limiting factor even in cases where the when mass flows increased three fold. The greatest limiting factor was determined to be the internal temperatures of the buildings, which set a strict limit and cannot be altered by Fortum without the customers’ cooperation. In conclusion a range of limiting factors were identified that proved to be potential limitations depending on the circumstances of a specific case. Depending on the investment needs in a specific case the economic viability was deemed to most likely be positive. When implementing lowered delivery temperatures in reality it is vital to acquiring data on secondary systems in order to identify the specific limitations of the proposed area. In addition an area of more research on the effects of lowered temperatures on the entirety of the grid as this study only investigates isolated sections.