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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Component based performance simulation of HVAC systems

Murray, Michael A. P. January 1984 (has links)
The design process of HVAC (Heating, Ventilation and Air Conditioning) systems is based upon selecting suitable components and matching their performance at an arbitrary design point, usually determined by an analysis of the peak environmental loads on a building. The part load operation of systems and plant is rarely investigated due to the complexity of the analysis and the pressure of limited design time. System simulation techniques have been developed to analyse the performance of specific commonly used systems: however these 'fixed menu, simulations do not permit appraisal of hybrid and innovative design proposals. The thesis describes research into the development of a component based simulation technique in which any system may be represented by a network of components and their interconnecting variables. The generalised network formulation described is based upon the engineer's schematic diagram and gives the designer the same flexibility in simulation as is available in design. The formulation of suitable component algorithms using readily available performance data is discussed, the models developed being of a 'lumped parameter' steady state form. The system component equations are solved simultaneously for a particular operating point using a gradient based non-linear optimisation algorithm. The application of several optimisation algorithms to the solution of RVAC systems is described and the limitations of these methods are discussed. Conclusions are drawn and recommendations are made for the required attributes of an optimisation algorithm to suit the particular characteristics of HVAC systems. The structure of the simulation program developed is given and the application of the component based simulation procedure to several systems is described. The potential for the use of the simulation technique as a design tool is discussed and recommendations for further work are made.
2

Veingeskolan F - Undersökning av inomhusmiljön samt en konstruktionsmässig utvärdering

Hansen, Henrik January 2007 (has links)
<p>Title: Veingeskolan F - Investigation of the indoor environment and a structural analysis</p><p>Method: Complete analysis of structural drawings to determine if the school have been constructed correctly. In my teorethical studies of the drawings I must seek out points that may have been damaged from moisture, this contains a full survey of the foundation, walls and ceiling. To strenghten the data collected from the drawings I must visit the school and do field investigations to find out if the school has any problems with the indoor environment.</p><p>Analysis: I determined that we had some damages on specific places, these damages was caused by leaking roofs, a carpet that was tarnished by strong sunlight in connection with some type of glue and also the ventilation that may have been drawing malodorous air from a shaft in the foundation.</p><p>Conclusion: I was able to see that the decision to demolish the school was quite drastic, if the county would have done continuous fixups on the construcion when the employes had complained maybe the action to the tear the school down would have been unnecessary. The lack of communication between the two parts lead up to the decision to demolish and build a complete new school.</p>
3

Veingeskolan F - Undersökning av inomhusmiljön samt en konstruktionsmässig utvärdering

Hansen, Henrik January 2007 (has links)
Title: Veingeskolan F - Investigation of the indoor environment and a structural analysis Method: Complete analysis of structural drawings to determine if the school have been constructed correctly. In my teorethical studies of the drawings I must seek out points that may have been damaged from moisture, this contains a full survey of the foundation, walls and ceiling. To strenghten the data collected from the drawings I must visit the school and do field investigations to find out if the school has any problems with the indoor environment. Analysis: I determined that we had some damages on specific places, these damages was caused by leaking roofs, a carpet that was tarnished by strong sunlight in connection with some type of glue and also the ventilation that may have been drawing malodorous air from a shaft in the foundation. Conclusion: I was able to see that the decision to demolish the school was quite drastic, if the county would have done continuous fixups on the construcion when the employes had complained maybe the action to the tear the school down would have been unnecessary. The lack of communication between the two parts lead up to the decision to demolish and build a complete new school.
4

Indoor environmental risk factors for respiratory symptoms and asthma in young children.

Rumchev, Krassi January 2001 (has links)
Asthma is a common chronic disorder in Western countries and is increasing in prevalence in both children and adults. Although genetic risk for atopy is an important factor for the development of asthma, it does not explain the tremendous increase in prevalence seen in recent decades. Environmental exposures in early life that affect immune maturation appear to be the key factors for the development of asthma. The indoor environment is a likely candidate since infants spend 90% of the time indoors at a time when immune deviation usually occurs. Exposure to indoor pollutants represents a potentially modifiable cause of allergic sensitization and asthma. In this context, it becomes important to establish which environmental factors might influence the development of asthma in predisposed individuals. Allergic reactions to certain environmental allergens such as house dust mites, cats, and cockroaches, have shown a high level of association with asthma prevalence, but in the last five years increasing attention is being paid to indoor environmental factors, other than allergens, that may be involved in the development of this disorder. The potential irritants include nitrogen dioxide, environmental tobacco smoke, formaldehyde, volatile organic compounds, and particulate matter (PM[subscript]2.5;10).The aim of the study was to examine the nature of the relationship between asthma and environmental exposure to indoor environmental irritants.A population based case-control study had been carried out in Perth, Western Australia. The study population consisted of young children (N = 192) aged between 6 months and 3 years old. Cases (n = 88) were asthmatic children who attended the Accident and Emergency Department at Princess Margaret Hospital for Children and were discharged with asthma as a primary diagnosis. Controls (n = 104) were children in the same age group as cases ++ / who had never been diagnosed with asthma, identified from birth records accessed through the Health Department of Western Australia. Information, regarding the respiratory conditions experienced by the study children and characteristics of the home, was collected using a standardised questionnaire. The questionnaire consists of questions about potential risk factors for asthma and these factors were grouped in three categories. The first category included information on personal and social factors such as age and gender of the child, and mother's and father's educational level. The second category was related to personal susceptibility factors such as child's allergy, parental and sibling's asthma, eczema and hay fever. The last category included environmental exposure in the house such as parental and visitors smoking inside the house, exposure to gas heating and cooking, kerosene space heaters, open fireplaces, and pets. Other questions related to environmental exposure were the presence of air conditioning, humidifiers, and type of floor covering in the child's bedroom and the living room. Measurements of indoor nitrogen dioxide (NO[subscript]2), formaldehyde (HCHO), volatile organic compounds (VOCs), particulate matter (PM[subscript]10), and house dust mite exposure were made on two occasions over one year, winter (middle June through September 1998) and summer (December 1998 through March 1999), Indoor temperature and relative humidity were also measured. The atopic status of the children was assessed by skin prick tests to common allergens.The study results indicated that age, gender, family history of asthma, atopy and domestic exposure to indoor environmental factors were significant predictors of asthma early in life. The study found that indoor exposure to formaldehyde, volatile organic compounds and house dust mite significantly increased the risk of ++ / having asthma. Presence of air conditioning appeared to be a protective factor for asthma.In conclusion, the study results confirmed the role of susceptibility factors in asthma and show that indoor environmental factors contribute as risk factors for asthma in early stage of fife. The observation that exposure to indoor air pollutants in early childhood is associated with asthma suggests the possibility that irritants in indoor air might be involved in the initiation phase of asthma. Since the quality of the indoor environment is potentially modifiable there might be opportunities for intervention to reduce asthma symptoms. In order to counteract the increasing prevalence in asthma, the significance of the indoor environment where children grow and spend most of their time need to be given greater attention.
5

Housing Conditions and Children's Respiratory Health

Wells, John A. 27 March 2014 (has links)
Understanding how respiratory health risks are associated with poor housing is essential to designing effective strategies to improve children’s quality of life. The objective of this thesis is to determine the relationship between the respiratory health of children and the condition of the homes in which they reside – using both building science and health data. The thesis therefore, examines the association between self-reported mould in the home, housing conditions, and the respiratory health of children. The study contributes to both the medical and engineering research community by enabling researches, designers, and Building Code officials to focus on cost-effective target areas for improving indoor air quality and thus, the respiratory health of children. A survey designed to assess the relationship between respiratory health and housing conditions was completed by 3,424 parents of grades 3 and 4 children in Winnipeg, Manitoba, Canada. Air samples were then taken in the homes of a subset of 715 houses– one in the child’s bedroom and another in the basement – with an exterior neighborhood air sample as a control measure. Engineering audits on 715 homes were then conducted – including measurements of relative humidity, temperature, and moisture content of walls. Major findings include the following: (1) Self-reported visible mould in the home is clearly associated with the presence of air-borne mould. (2) There are fewer healthy children when mould is present in the home. (3) Cladosporium levels (CFU/m3) in the house were associated with children’s asthma in combination with persistent colds. (4) Measures taken by homeowners to increase the air-tightness of their homes, such as new windows increased the likelihood of having higher air-borne moisture and mould levels. (5) The “hygiene hypothesis” was supported, which postulates that denying children access to certain types and levels of biological contamination at a young immune-developmental age, increases their susceptibility to allergic responses at a later age.
6

Measurement and Modeling of Polybrominated Diphenyl Ethers (PBDEs) and Polychlorinated Biphenyls (PCBs) in the Indoor Environment

Zhang, Xianming 26 February 2009 (has links)
The indoor environment is a potentially dominant source of exposure for polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). This thesis describes a study on levels, sources, emissions, and fate of PBDEs and PCBs indoors. PBDEs and PCBs air levels in 20 indoor environments in Toronto were sampled and measured. The geometric means of PBDE (Σ10BDE) and PCB (Σ35PCB) concentrations were 0.072 and 7.2 ng m-3 respectively. Statistical analysis on chemical profiles distinguished the chemical sources in the 20 environments. A multimedia indoor environmental model was applied on two test rooms. Estimated PBDE and PCB emission rates were 5.4-550 ng h-1 and 280-5870 ng h-1 respectively. Particle movement dominates within-room transport processes, and dust removal and air advection are the main chemical loss processes. Temperature, particle concentration and deposition velocity, and air exchange rate are the most influential parameters, which can alter source or sink behaviors of household products for the chemicals.
7

Measurement and Modeling of Polybrominated Diphenyl Ethers (PBDEs) and Polychlorinated Biphenyls (PCBs) in the Indoor Environment

Zhang, Xianming 26 February 2009 (has links)
The indoor environment is a potentially dominant source of exposure for polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). This thesis describes a study on levels, sources, emissions, and fate of PBDEs and PCBs indoors. PBDEs and PCBs air levels in 20 indoor environments in Toronto were sampled and measured. The geometric means of PBDE (Σ10BDE) and PCB (Σ35PCB) concentrations were 0.072 and 7.2 ng m-3 respectively. Statistical analysis on chemical profiles distinguished the chemical sources in the 20 environments. A multimedia indoor environmental model was applied on two test rooms. Estimated PBDE and PCB emission rates were 5.4-550 ng h-1 and 280-5870 ng h-1 respectively. Particle movement dominates within-room transport processes, and dust removal and air advection are the main chemical loss processes. Temperature, particle concentration and deposition velocity, and air exchange rate are the most influential parameters, which can alter source or sink behaviors of household products for the chemicals.
8

Návrh podnikové strategie společnosti JC STAV s.r.o.

Hlaváčová, Miroslava January 2011 (has links)
No description available.
9

An Energy Audit of Kindergarten Building in Vallbacksgården

Liu, Xiaojing, Zhang, Taoju January 2015 (has links)
Energy consumption rises continuously every year. Globally, buildings count for half of electricity consumption and 20%-40% of total energy consumption. Building energy sector consumed 40% of total energy use in Sweden. The vital of reduce energy consumption is to enhance building efficiency. This energy audit work investigates how energy consumes of kindergarten building in Vallbacksgården. Then give out cost effective suggestions to improve energy efficiency for object building. The result shows total amount of energy input of the building is equal to 241.9 MWh. While district heating takes the largest part of energy input that correspond to 188.9 MWh (78%), and cost around 123500 Kr annually. Furthermore, energy 38.0 MWh (16%) is contributed by solar radiation, which becomes second largest source of energy input. Finally, internal heat generation is the smallest contributor of energy input which counts 15.0 MWh (6%). For energy output, majority of heat loss is leaded by transmission losses. It cost 190.4 MWh per year that shares 79% of total energy output. Nature ventilation losses of object building shares 17% of total heat output which is 41.7 MWh. Mechanical ventilation and hot tap water have energy consumption with 7.8 MWh and 2.0 MWh respectively. They take rest 4% of total energy output. According to the finding, several reasonable suggestions will be given. Firstly, for the costless solution, decreasing indoor temperature 1℃ or 2 ℃ is able to reduce heating demand 9.0 MWh or 18.1 MWh annually. It will reduce CO2 emission 131859g- 266070 g, and save 5274 – 10642 SEK per year. Secondly, substitute district heating systems by ground source heat pump is an environmental solution. Using ground source heat pump has priority of environment, which lower CO2 emission 1909200 g/year and save 68262 SEK/year by analyze. Investment for this solution is 979000 SEK and the payback time takes 14.3 year. Replace old windows is a moderate solution of cost. Substitution by using energy glass can reduce 20.9 MWh heating demand and 307377 g CO2 every year. New energy glass windows can cut 13591 SEK for district heating every year. The renovate investment and payback time are more than 159732 SEK and 11.8 year respectively.
10

Comparison between three different CFD software and numerical simulation of an ambulance hall

Li, Ning January 2015 (has links)
Ambulance hall is a significant station during emergency treatment. Patients need to be transferred from ambulance cars to the hospital’s building in the hall. Eligible performance of ventilation system to supply satisfied thermal comfort and healthy indoor air quality is very important. Computational fluid dynamic (CFD) simulation as a broadly applied technology for predicting fluid flow distribution has been implemented in this project. There has two objectives for the project. The first objective is to make comparison between the three CFD software which consists of ANSYS Fluent, Star-CCM+ and IESVE Mcroflo according to CFD modeling of the baseline model. And the second objective is to build CFD modeling for cases with difference boundary conditions to verify the designed ventilation system performance of the ambulance hall. In terms of simulation results from the three baseline models, ANSYS Fluent is conclusively recommended for CFD modeling of complicated indoor fluid environment compared with Star-CCM+ and IESVE Microflo. Regarding to the second objective, simulation results of case 2 and case 3 have shown the designed ventilation system for the ambulance hall satisfied thermal comfort level which regulated by ASHRAE standard with closed gates. Nevertheless, threshold limit value of the contaminants concentration which regulated by ASHRAE IAQ Standard cannot be achieved. From simulation results of case 4.1 to 4.3 shown that the designed ventilation system cannot satisfy indoor thermal comfort level when the gates of the ambulance hall opened in winter. In conclusion, measures for decreasing contaminants concentration and increasing indoor air temperature demanded to be considered in further design.

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