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1
MacKinnon, Ian R. (Ian Roderick) 1964. "Air distribution from ventilation ducts." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59655.
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A wooden, perforated, uniform cross-section duct was examined to determine the optimum levels of aperture ratio and fan speed with respect to uniformity of discharge. The optimum aperture ratio for the 8.54 m long duct was 1.0 with a uniformity coefficient of 90.28%. The fan speed had little effect on the uniformity of discharge. The friction factor was experimentally determined to be 0.048 for a non-perforated duct and this value was assumed to be the same for a perforated duct of similar construction. A kinetic energy correction factor was used to analyze the flow in the duct. Values for this correction factor were determined from experimental data. Values of the coefficient of discharge and the total duct energy were calculated. A mathematical model was proposed based on the conservation of momentum and the Bernoulli's equation. The model responded favourably and predicted the duct velocity nearly perfectly and slightly underestimated the total duct energy.
2
Kinsman, Roger Gordon. "Outlet discharge coefficients of ventilation ducts." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59271.
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Discharge coefficients are an important parameter in the prediction of the air displacement performance of ventilation outlets and in the design of ventilation ducts.Discharge coefficients of a wooden ventilation duct 8.54 metres in length and of a constant 0.17 m$ sp2$ cross sectional area were measured. Four different outlet shapes and 3 aperture ratios of each shape were tested. A split plot experimental design was used to evaluate the effect of outlet shape, outlet size, and distance from the fan on discharge coefficient. The relationship between duct performance characteristics and discharge coefficient was examined. A mathematical equation to predict the discharge coefficient was developed and tested.
Discharge coefficient values measured ranged from 0.19 to 1.25 depending on the aperture ratio and distance from the fan. Outlet shape had no significant effect. The apparent effects of aperture ratio and size are due to the effects of head ratio. The equation predicting the discharge coefficient had a maximum error of 5 percent for the aperture ratios of 0.5 and 1.0, and 15 percent at an aperture ratio of 1.5.
3
Balasubramanian, Vivek. "Effectiveness of the "common" method in balancing exhaust ventilation systems." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4354.
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Thesis (M.S.)--West Virginia University, 2005.Title from document title page. Document formatted into pages; contains vii, 59 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 48-49).
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El, Moueddeb Khaled. "Principles of energy and momentum conservation to analyze and model air flow for perforated ventilation ducts." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=42024.
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A theoretical model was developed to predict the air distribution pattern and thus to design perforated ventilation ducts equipped with a fan. The analysis of the air distribution pattern of such systems requires accurate measurement procedures. Several experimental methods were tested and compared. Accordingly, the piezometric flush taps and thermo-anemometer were selected to measure respectively the duct air pressure and the outlet air flow.Based on the equations of energy and momentum conservation, a model was formulated to predict the air flow performance of perforated ventilation ducts and to evaluate the outlet discharge angle and the duct regain coefficients without evaluating frictional losses. The basic assumptions of the model were validated by experimentally proving the equivalence of the friction losses expressed in the 2 cited equations. When compared to experimental results measured from four wooden perforated ventilation ducts with aperture ratios of 0.5, 1.0, 1.5, and 2.0, the model predicted the outlet air flow along the full length of perforated duct operated under turbulent flow conditions with a maximum error of 9%. The regain coefficient and the energy correction factor were equal to one, and the value of the discharge coefficient remained constant at 0.65, along the full length of the perforated duct. The outlet air jet discharge angle varied along the entire duct length, and was not influenced by friction losses for turbulent flow.
Assuming a common effective outlet area, the model was extended to match the performance of the fan and the perforated duct and to determine their balance operating point.
5
Fu, Yan. "Modelling of ducted ventilation system in agricultural structures." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60519.
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Air distribution ducts are used in the environmental control of livestock and poultry building as well as the conditioning of most agricultural produce.In order to simplify the approach to the design of ventilation ducts, a mathematical equation has been derived to describe the average air velocity of a duct.
The primary objective of the research work was to test goodness of fit of an equation describing the average air velocity of perforated ventilation ducts, under balanced as well as unbalanced air distribution: $V = H sb{o}{X over L} + (V sb{L}-H sb{o}) {X sp2 over L sp2}$.
This equation was successfully tested using data measured from 14 ducts of constant cross-sectional area, built of wood or polyethylene with outlets of various shapes and aperture ratios. Results indicated that aperture ratio and distance along the duct are the two most significant factors influencing the average duct air velocity values, but material and outlet shape had little effect.
6
El, Moueddeb Khaled. "Principles of energy and momentum conservation to analyze and model air flow for perforated ventilation ducts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ29929.pdf.
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Khaire, Swapnil S. "Influence of test section entrance conditions on straight flat oval apparent relative roughness a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=0&did=2000385011&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1277822700&clientId=28564.
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Besarla, Dhaman Kumar. "Modeling and optimization of air flow in a cabin air filtration test duct a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2008. http://proquest.umi.com/pqdweb?index=0&did=1679682361&SrchMode=1&sid=2&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1254155722&clientId=28564.
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Sanchez, Marc. "Etude des extracteurs d'air hybrides éoliens : conception de géométries et analyse des écoulements." Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0040/document.
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Ce travail de thèse concerne l'étude d'extracteurs d'air hybrides éoliens. Il se décompose en des investigations amont et appliquées. Dans la partie amont, des simulations fines ont été effectuées en conduite carrée avec et sans rotation, pour des nombres de Reynolds turbulents de l'ordre de 600, afin d'analyser l'impact de la rotation sur la turbulence. Elles ont montré que la rotation rompt la symétrie de l'écoulement. La partie appliquée est dédiée à la conception d'une nouvelle géométrie d'extracteur d'air. Cette géométrie a été proposée à partir de l'analyse de simulations RANS. Ses performances ont été confirmées par des mesures expérimentales sur banc d'essais. Les tests en soufflerie d'un système de captage d'énergie éolienne, conçu pour l'extracteur, ont mis en évidence son adéquation au régime de fonctionnement de l'extracteur. Les essais expérimentaux de l'extracteur complet, montrent que le système de captage apporte une part significative de l'énergie. Des essais en soufflerie ont permis d'observer le comportement global de l'extracteurThis PhD work concerns the study of hybrid air extractors. It is composed of upstream and applied investigations. In the upstream part, fine simulations are realized in square duct flow with and without rotation to analyse the impact of rotation on turbulence. It is found that rotation removes symmetry property of the flow with turbulent Reynolds number of 600. The applied part is dedicated to the conception of a new air extractor geometry. This geometry is proposed from the analyse of RANS simulations. Its performances are confirmed by experimental measurements on test rig. Wind tunnel tests of a wind power capturing system, designed for the extractor, show a good adequation to the operating regime of the extractor. Experimental investigations on the complete air extractor, show the wind power capturing system brings a significant part of the energy. Wind tunnel tests allow to observe the complete air extractor behaviour
10
Trinder, M. C. J. "Active noise control in finite length ducts." Thesis, University of Essex, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371924.
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Mak, Cheuk-Ming. "The application of computational fluid dynamics to the prediction of regenerated noise in ventilation systems." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321131.
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Tsui, Ka-cheung. "Neighborhood ventilation of a building cluster by combined forces." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B42182128.
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Lane-Serff, Gregory. "Heat flow and air movement in buildings." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276888.
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Jangam, Ranjit. "Relationship between damper resistance and damper insertion depth." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4509.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xi, 97 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 62-63).
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Judy, Christopher Daniel Shon Paul. "Evaluating the effects of elbows and duct size on the accuracy of hand-held pitot traverse flow measurements." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5479.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains v, 44 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 39-40).
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Abdul, Ghani S. A. A. "An investigation into water ingress through ground vehicle heating ventilation and air conditioning unit." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268509.
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Aguirre, Sánchez Mikel. "Air flow disturbance by moving objects at local exhaust ventilation." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-19719.
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The present thesis aims to study the effect of human movements on local exhaust ventilation. In its simplest terms, local exhaust ventilation is a system which has the function of extracting contaminated air situated close to the contaminant source, protecting a working person from exposure to hazardous substances by containing or capturing them locally, at the emission point. As an important security measure referred to terms of health, it is crucial for the healthiness of workers to control and prevent them from the exposure to vapour, mist, dust or other airborne contaminants. Additionally, to a lesser degree of significance, it can be stressed an expected increase in worker performance due to an improvement of the working conditions. There is an existing necessity for well-defined and appropriate methods to test the performance of local exhaust devices in order to reach standard efficiency values. The lack of an international standardization led to the realization of this study, which, ultimately, has the purpose of obtaining relevant results that can be utilized for future normalized test procedures. The study entails full scale experimental measurements that include air velocity measurements in 3 dimensions, a local exhaust ventilation device with circular hood and a flat flanged plate and a controlled generation of air turbulence through physical movements of a human-sized cylinder, simulating a walking person. The present study extends previous similar studies at the University of Gävle, where the controlled air turbulence was generated by a moving plate. After meaningful results obtained in that study, one of the considerations was to better simulate a walking person, by replacing the plate for a movable cylinder. The present study points at a larger similarity occurring with a cylinder than with a plate, as regards the air flow pattern produced by a real walking person. As in the previous study, the Percentage of Negative Velocities, PNV, has been used as the main measure of turbulence induced risk of contaminant spread. The PNV represents the fraction of the time when the flow is directed opposite to the suction air stream in front of the local exhaust hood. The obtained results conclude that the use of the cylinder as a moving object has been an improvement to simulate the effect of the movement of a human being on a relaxed walking pace. The present study was carried out in parallel with the thesis work by Leyre Catalán Ros, which complements this study by analyzing the effect of an added heated dummy, simulating a person seated in front of the local exhaust device.
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Wrisdale, Ian Edward. "Flow prediction for three-dimensional intakes and ducts using viscous-inviscid interaction methods." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293854.
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Tsui, Ka-cheung, and 徐家祥. "Neighborhood ventilation of a building cluster by combined forces." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B42182128.
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Jouini, Dhafer Ben Mahmoud Carleton University Dissertation Engineering Mechanical. "Experimental investigation of the ventilation air flow properties in an office space." Ottawa, 1992.
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Grbál, Jakub. "Analýza větrání banky." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409864.
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The aim of the diploma thesis is the simulation of different types of air conditioners using the CFD methods. The main goal of this thesis is to design the most suitable type of air conditioning in the consideration room, due to the air flow rate in the residental area. The conclusion of the work is to devote the design of air conditioning system with the application of selected type of air conditioning based on the results of CFD simulations.
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McBrien, Robert K. 1958. "Pressure measurements for periodic fully developed turbulent flow in rectangular interrupted-plate ducts." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65434.
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Mohammad, W. S. "Space air-conditioning of mechanically-ventilated rooms : computation of flow and heat transfer." Thesis, Cranfield University, 1986. http://hdl.handle.net/1826/4022.
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Computational studies of two- and three-dimensional, turbulent
recirculating flows within mechanically-ventilated enclosures are
reported. Two principal cases are examined: (i) two-dimensional
offset jets: and (ii) three-dimensional flow induced in rooms by
supply jets emanating from low or high side-wall registers. The
calculations were undertaken using iterative finite-domain proceedures
which solve the conservation equations for mass, momentum and
enthalpy, together with additional transport equations for the
turbulent kinetic energy and its dissipation rate . The effect of
buoyancy waS. explicitly accounted for when modelling these equations,
in order that they could be employed to simulate buoyant flow in
ventilated rooms. Computations of the mean velocity, temperature and
convective heat transfer distribution are reported, and compared with
experimental data where available.
A modified version of the two-dimensional elliptic code of Pun
and Spalding (1977) was employed to simulate the offset jet case.
These involve the discharge of a turbulent jet parallel to a flat
surface and eventually attaching to it. The investigations covered a
wide range of offset ratio (3.5-32.4). and the computed flow
properties are compared with measurements from several sources. These
comparisons show good agreement downstream of the reattachment point,
while some discrepancies are evident upstream from this location. The
differences therefore occur mainly in the recirculating flow region,
and are believed to arise from shortcoming in the starting profiles,
the turbulance model and the treatment of the near-wall flow.
A three-dimensional elliptic finite-domain code was developed to
simulate the complex, jet-induced flow within rectangular enclosures.
The code was verified using both laminar and turbulent flow test cases
on simpler geometries. Comparisons with the measurements and
predictions reported by previous researchers were employed for this
purpose. Subsequentlyr the ventilated room simulations were
undertaken using three different ventilation arrangements with thermal
conditions corresponding to isothermall non-buoyant (constant
property) and buoyancy"affected flows. The computations were again
compared with experimental and numerical predictions of previous
researchers. This comparison displayed generally good agreement with
these sources.
A study of the flow and convective heat exchange within a
warm-air heated rom, for which buoyancy effects are significant# is
also reported in a bound paper (Alamdari, Hammonda nd Mohammad, 1986)
for three different heat loads. Its aim to assess the balance between
accuracy and economy provided by the present higher-level method
compared with the intermediate-level convection model of Alamdari and
Hammond (1982) when used to supply building thermal simulation
programs with accurate convection heat transfer data. The computed
results of both models were compared, and indicate that the
intermediate-level is a valuable alternative source that can satisfy
the needs of building thermal modellers. It provides resonable
accuracy at a very modest cost in computing terms.
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Li, Fan. "Application of computational fluid dynamics to the study of air flow in buildings." Thesis, University of Westminster, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283467.
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Ip, Kenneth C. W. "Dynamic modular simulation of variable water and air volume flow systems in buildings." Thesis, University of Bristol, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251526.
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Hill, S. D. "Casing treatment for an industrial axial flow fan." Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241843.
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Al-Nizari, Hamdan Omar A. "Dynamic performance and refrigerant flow control in refrigeration systems." Thesis, Brunel University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315452.
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Houston, Stephen Douglas. "Tube-side flow and heat transfer in package boilers." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/804.
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Basharhagh, M. Zia. "Recess vane passive stall control for axial flow fans." Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305269.
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El-Hawat, Salem M. "Numerical modelling of flow and heat transfer for high-performance surfaces." Thesis, University of Brighton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251804.
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Tough, M. C. "A heat transfer model of forced convection, cross flow heat exchangers used in space heating." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259171.
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Viguer, Torres Luis, and Perez Borja Fatas. "Computer simulations of temperature and flow field in industrial spaces using confluent jets air supply method." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-12409.
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Ventilation systems are closely connected to indoor environment. In industrial spaces it has a major impact due to air quality and thermal comfort requirements, which leads into health and economy improvements. Confluent jets ventilation system has been assess in Söderhamn Eriksson, a machinery company located in Mariannelund, Sweden, since it has been proved as the best ventilation performance. Moreover this system is worthy for both heating and cooling purposes, although just heating case will be developed in this thesis. By means of modelling software such as Gambit and Airpak, the company’s case could have been analyzed via Computational Fluid Dynamics (CFD) software, i.e. Fluent. The analyzed models were accepted after a thorough study of meshing parameters, bearing in mind computational limitations. Every temperature data gathered from simulation results has been verified with infrared camera figures taken at the company, thus contributing to reach reliable conclusions. As it is inferred from previous papers and empiric theory, the flow field observed is also justified. Then, thermal comfort and air quality analysis relies on consistent facts. It has been found that current ventilation at the company is slightly misadjusted, since supplied air’s temperature and velocity are slightly off point. Therefore, it is recommended to reduce these values to reach better working environment.
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Myjavec, Patrik. "Optimalizace vzduchotechniky výrobní haly." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-391909.
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Diploma thesis is divided into two parts. The theoretical part deals with natural ventilation and the practical part focuses on the optimization of the ventilation in the original hall using CFD simulation. One of the solutions is proposed in the design part of the diploma thesis.
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Massey, Kevin C. "Flow/acoustic coupling in heated and unheated free and ducted jets." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/11971.
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Ho, Son Hong. "Numerical simulation of thermal comfort and contaminant transport in air conditioned rooms." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000548.
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Štencel, Bedřich. "Distribuce vzduchu při větrání bytů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225398.
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My thesis is divided into three separate parts. The first part is devoted to the theoretical part of the ventilation systems. The second part deals with the determination of the conditions for a number of air exchange, a comparison of three variants of the location of air outlets in dwelling units and the application image airflow from experimental measurements on the common room. The third part is focused on the description of the experimental tasks in the laboratory at the Institute building services.
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Bombera, Jiří. "Simulace koncových elementů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371836.
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The aim of the diploma thesis is the simulation of air valves and difusers using CFD. The goal of this thesis is to determinate the type of air valve and diffusor, which would ventilate the room of a detached house the best – considering the speed of the airflow and the age of the air. Outcome of this work is the design of the air conditioning system for a detached house with application of the air valve and difuser which is evaluated as the ideal option for the ventilation in the room.
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Johansson, Tom, and Viktor Ryberg. "Val av ventilationssystem för kontorsverksamhet : En kostnadsjämförelse." Thesis, KTH, Byggteknik och design, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-149462.
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Enligt Folkhälsomyndighetens uppgifter påstår 18 procent av den vuxna populationen att de lider av symtom relaterat till inomhusmiljön. Symtomen kan beröra alldagliga ohälsor däribland trötthet och huvudvärk till allvarliga åkommor såsom cancer (Folkhälsomyndigheten, 2013). Då ventilationens huvuduppgift är att tillgodose kraven på inomhusklimatet och därmed förebygga ohälsa, berör detta examensarbete problematiken kring ventilationssystemets utformning och dess ekonomiska konsekvenser. Syftet med arbetet var att identifiera vilken luftflödesprincip som är kostnadseffektivast för kontorsverksamhet utifrån två skilda typplanlösningar. Tre luftflödesprinciper har studerats, där slutligen ett CAV-, VAV- och DCV- system har utformats och dimensionerats utifrån realistiska förutsättningar och krav berörande inomhusklimatet. Ventilationssystemen utformas på skilda sätt med avseende på vilken luftflödesprincip som används, vilket bidrar till ekonomiska för- och nackdelar. Den ekonomiska undersökningen utförs genom jämförelser utifrån respektive ventilationssystems livscykelanalys, där luftflödesprinciper med likartade förutsättningar studeras i förhållande till varandra. Rapporten hanterar generella problem och tillvägagångssätt gällande problematiken kring dimensionering och utformning av ventilationssystem. De ekonomiska analyserna har resulterat i tydliga skillnader gällande investering-, drift- och underhållskostnader för respektive system. Resultatet påvisar att investeringskostnaden är den viktigaste faktorn vid val av ventilationssystem.According to Folkhälsomyndigheten, 18 precent of the adult population claims they experience symptoms related to the indoor environment. These symptoms can consist of both common illnesses, such as fatigue and headache, to more serious diseases such as cancer (Folkhälsomyndigheten, 2013). The main task of a ventilation system is to satisfy the requirements regarding the indoor climate and thereby consequently prevent poor health. This report focuses on the complex problems regarding ventilation systems design and it´s economic consquences. The purpose with this report is to identify which airflow principle is the most cost effective for office operations basad on two distinct floor plans. Three airflow principles have been studied; consist of the CAV-, VAV- and DCV-principle. All principles were designed and dimensioned based on realistic conditions and the specific requirement regarding the indoor environment. Each ventilation system was designed differently depending on the applied airflow principle, which led to different economic pros and cons for each ventilation system. The airflow principle´s life cycle cost has been compared in an economic analysis. The economic analysises were based on comparisons between each ventilation system’s life cycle cost and it´s reigning conditions. The report deals with general problems and processes regarding the dimensioning and designing of the ventilation systems. The economic comparisons resulted in a substantial difference in investment- , operation- and the maintenance cost for each system. The results proved that the investment cost is the key factor when comparing the airflow principle´s life cycle cost.
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O'Sullivan, Paul D. "Experimental study of single sided ventilation through a multi-configuration slotted louvre system." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/16416.
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Evidence based performance of novel ventilation systems in existing low energy buildings is invaluable as it provides data on the system operation in a real dynamic environment. This thesis presents the outcomes from research involving a number of experimental field studies of a single sided ventilation system installed in a single cell office space as part of a building retrofit pilot project in Cork, Ireland. The solution consists of a purpose provided, multi configuration opening, comprising a narrow slotted architectural louvre component split across a low level manual opening section and a high level automated opening section. A review of published research found that little experimental data exists on the performance of such systems and air flow rate correlations developed for plain openings are currently used by designers to make predictions about their performance. Three experimental campaigns were designed and carried out. First, in order to quantify performance of the system, long term and short term monitoring of the internal thermal and air flow environment at the experimental building was completed. Second, ventilation rate measurements in existing and retrofit spaces were completed using a tracer gas concentration decay technique. Thirdly, air flow through the single sided slot louvre opening was investigated. In addition, the annual cooling potential of the multi-configuration system was investigated computationally. Results show there was a significant difference between both thermal environments with the retrofit space consistently displaying lower air temperatures over the cooling season and throughout all Air Change Rate measurement periods. Lower levels of vertical thermal stratification and diurnal temperature variation were also observed. On average, across a wide range of boundary conditions, lower ventilation rates were observed for the slotted louvre system with a narrower spread of values when compared with the existing building. The dominant driving force was either buoyancy or wind depending on the opening configuration adopted in the slotted louvre system. The slot louvre was found to be wind dominant for lower opening heights when compared with a plain opening of the same dimensions. Existing single sided correlations were found to perform better when predicting airflow rates through a plain opening when compared with the slot louvre system and a new dimensionless exchange rate parameter is proposed for predicting wind driven airflow through the slot louvre. Simulations indicate that 80% of annual occupied hours required an enhanced ventilative cooling airflow rate to achieve internal thermal comfort. Using a combination of configurations the system was able to provide the required cooling airflow rate for 93% of the occupied hours.
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Ahlgren, Tobias, and Jalal Eliassi. "Värmeförluster vid utvändigt placerade ventilationssystem." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-20676.
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To be able to handle tomorrows need for limited energy consumption we need to reduce our use of energy. The building sector stands for around 40 % of all energy consumption in the society. The government has put up a goal to reduce the energy consumption in our buildings with 20 % by year 2020 and 50 % by year 2050 compared with year 1995. To be able to do reach that goal we need a more energy efficient building stock. The main part of the energy used in our buildings is used for space heating. By installing ventilation systems with heat recovery on the exhaust air it is possible to use the heat-energy in the exhaust air to warm up the incoming air. This can contribute to a reduction in energy use. A ventilation system with heat recovery on the exhaust air is space demanding and there can be problems with finding enough space to do the installation indoors. Therefore it can be an advantage to place the aggregate and the ducts on the outside of the buildings climate shell. A placement exterior of the buildings climate shell or in an unheated space leads to thermal heat losses. The aim with this essay is to investigate how significant the heat losses are on exterior placed ventilation systems. The investigation has been done with help of theoretical calculations and measurements of the temperature difference in the ventilation ducts. Analysis has been made on life cycle costs on how to reduce the heat losses in an economic manner. To buildings, Höstvägen 14 and 22 in Växjö, which have been equipped with exterior placed ventilation systems have been studied. The two buildings have two different types of installation of the ducts. Our result shows that the heat losses through the ventilation systems on Höstvägen 14 and 22 are significant. The majority of the losses occur in the ducts. In the aggregate the thermal bridges in the framework accounts for the larger part.
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Hayati, Abolfazl. "Natural Ventilation and Air Infiltration in Large Single‑Zone Buildings : Measurements and Modelling with Reference to Historical Churches." Doctoral thesis, Högskolan i Gävle, Energisystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-24612.
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Natural ventilation is the dominating ventilation process in ancient buildings like churches, and also in most domestic buildings in Sweden and in the rest of the world. These buildings are naturally ventilated via air infiltration and airing. Air infiltration is the airflow through adventitious leakages in the building envelope, while airing is the intentional air exchange through large openings like windows and doors. Airing can in turn be performed either as single-sided (one opening) or as cross flow ventilation (two or more openings located on different walls). The total air exchange affects heating energy and indoor air quality. In churches, deposition of airborne particles causes gradual soiling of indoor surfaces, including paintings and other pieces of art. Significant amounts of particles are emitted from visitors and from candles, incense, etc. Temporary airing is likely to reduce this problem, and it can also be used to adjust the indoor temperature. The present study investigates mechanisms and prediction models regarding air infiltration and open-door airing by means of field measurements, experiments in wind tunnel and computer modelling. In natural ventilation, both air infiltration and airing share the same driving forces, i.e. wind and buoyancy (indoor-outdoor temperature differences). Both forces turn out to be difficult to predict, especially wind induced flows and the combination of buoyancy and wind. In the first part of the present study, two of the most established models for predicting air infiltration rate in buildings were evaluated against measurements in three historical stone churches in Sweden. A correction factor of 0.8 is introduced to adjust one of the studied models (which yielded better predictions) for fitting the large single zones like churches. Based on field investigation and IR-thermography inspections, a detailed numerical model was developed for prediction of air infiltration, where input data included assessed level of the neutral pressure level (NPL). The model functionality was validated against measurements in one of the case studies, indicating reasonable prediction capability. It is suggested that this model is further developed by including a more systematic calibration system for more building types and with different weather conditions. Regarding airing, both single-sided and cross flow rates through the porches of various church buildings were measured with tracer gas method, as well as through direct measurements of the air velocity in a porch opening. Measurement results were compared with predictions attained from four previously developed models for single‑sided ventilation. Models that include terms for wind turbulence were found to yield somewhat better predictions. According to the performed measurements, the magnitude of one hour single-sided open-door airing in a church typically yields around 50% air exchange, indicating that this is a workable ventilation method, also for such large building volumes. A practical kind of diagram to facilitate estimation of suitable airing period is presented. The ability of the IDA Indoor Climate and Energy (IDA-ICE) computer program to predict airing rates was examined by comparing with field measurements in a church. The programs’ predictions of single-sided airflows through an open door of the church were of the same magnitude as the measured ones; however, the effect of wind direction was not well captured by the program, indicating a development potential. Finally, wind driven air flows through porch type openings of a church model were studied in a wind tunnel, where the airing rates were measured by tracer gas. At single-sided airing, a higher flow rate was observed at higher wind turbulence and when the opening was on the windward side of the building, in agreement with field measurements. Further, the airing rate was on the order of 15 times higher at cross flow than at single-sided airing. Realization of cross flow thus seems highly recommendable for enhanced airing. Calibration constants for a simple equation for wind driven flow through porches are presented. The measurements also indicate that advection through turbulence is a more important airing mechanism than pumping. The present work adds knowledge particularly to the issues of air infiltration and airing through doors, in large single zones. The results can be applicable also to other kinds of large single-zone buildings, like industry halls, atriums and sports halls.Naturlig ventilation är den dominerande ventilationsprocessen i äldre byggnader såsom kyrkor, och även i de flesta småhus i Sverige och övriga delar av världen. Luftinfiltration och vädring utgör viktiga komponenter i naturlig ventilation, där luftinfiltration är luftflöde genom oavsiktliga läckage i byggnadsskalet, medan vädring är avsiktligt luftutbyte genom stora öppningar såsom fönster och dörrar/portar. Vädring kan i sin tur ske ensidigt (genom en öppning) eller som tvärdrag (genom två eller flera öppningar belägna på olika ytterväggar). Det totala luftutbytet påverkar värmeförluster och inomhusluftens kvalité. I kyrkor orsakar avsättning av luftpartiklar en gradvis nedsmutsning av invändiga ytor, inklusive väggmålningar och andra konstföremål. Betydande mängder partiklar avges från besökare, tända ljus, rökelse, o.d. Tillfällig vädring kan minska detta problem, men även användas för att justera innetemperaturen. Föreliggande studie analyserar mekanismer och predikteringsmodeller gällande luftinfiltration och dörrvädring genom fältmätningar, vindtunnelförsök och datorsimuleringar. Luftinfiltration och vädring har samma drivkrafter, d.v.s. vind och termik (inne‑ute temperaturskillnader). Båda dessa drivkrafter är svåra att predicera, särskilt vindinducerade flöden och kombinationen av termik och vind. Två av de mest etablerade modellerna för luftinfiltrationsprediktering i byggnader har utvärderats via mätningar i tre kulturhistoriska stenkyrkor i Sverige. En korrigeringsfaktor av 0,8 föreslås för bättre prediktion av den ena modellen (som gav bäst resultat) gällande höga en-zonsbyggnader såsom kyrkor. En detaljerad numerisk modell är utvecklad för luftinfiltrationsprediktering, där indata baseras på fältundersökningar, inkl. IR-termografering och uppmätt av neutrala tryckplanet (NPL). Modellens funktionalitet har validerats via mätningar i en av fallstudierna och pekar på tämligen god prediktionsprestanda. Vidare utveckling av modellen föreslås, inkl. ett mer systematiskt kalibreringssystem, för olika typer av byggnader och väderförhållanden. Gällande vädring mättes både ensidigt flöde och tvärdrag genom portar i olika kyrkobyggnader med hjälp av spårgas samt direkta lufthastighetsmätningar i portöppning. Mätresultaten jämfördes med erhållna prediktioner från fyra tidigare utvecklade modeller för ensidig ventilation. De modeller som tog hänsyn till vindturbulens gav något bättre resultat. Enligt utförda mätningar medför en timmes ensidig portvädring i en kyrka cirka 50 % luftutbyte, vilket indikerar att detta är en tillämpbar ventilationsmetod, även för så pass stora byggnadsvolymer. Ett särskilt vädringsdiagram presenteras, som syftar till att underlätta uppskattning av erforderlig vädringsperiod. Vidare studerades predikteringsprestanda hos IDA Indoor Climate and Energy (IDA-ICE) simuleringsprogram avseende vädring, där simuleringsdata jämfördes med fältmätningar i en kyrka. Programmets prediktion av ensidigt luftflöde genom en öppen kyrkport var av samma storlekordning som det uppmäta; dock klarade programmet inte av att hantera inverkan av vindriktning så väl, vilket pekar på en utvecklingspotential. Avslutningsvis undersöktes vinddrivet flöde igenom portöppningar i en kyrkmodell i vindtunnel, där luftomsättningen mättes med hjälp av spårgasmetoden. Vid ensidig vädring observerades högre flöde vid högre vindturbulens och när öppningen var på vindsidan av byggnaden, i överensstämmelse med fältmätningarna. Dessutom var vädringsflödet vid tvärdrag i storleksordningen 15 högre än det vid ensidig vädring. Det verkar alltså som att man kan öka vädringstakten avsevärt om man kan åstadkomma tvärdrag. Kalibreringskonstanter presenteras också för en enkel ekvation för vinddrivet flöde genom portar. Vindtunnelstudien indikerar vidare att advektion genom turbulens är en viktigare vädringsmekanism än pumpning. Föreliggande arbete bidrar med kunskap speciellt kring luftinfiltration och vädring genom portar i höga en-zonsbyggnader. Resultaten kan även vara tillämpliga på andra typer av höga en-zonsbyggnader såsom industrihallar, atrier/ljusgårdar och idrottshallar.
Church project
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Ekl, Martin. "Experimentální stanovení charakteristik proudění vzduchu z distribučních prvků." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226017.
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The thesis is aimed at the problem of the air distribution in buildings. The object of research is the concert hall. The thesis contains three different technical proposals and technical views of the microclimate concert hall. The microclimate’s solutions are focused on the air distribution in the hall. The part of the thesis is an experiment. The experiment continues on the one of the technical proposals. Its purpose is to determine the characteristics of air flowing from distribution element.
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Kanaani, Hussein. "Real time detectionof airborne fungal spores and investigations into their dynamics in indoor air." Queensland University of Technology, 2009. http://eprints.qut.edu.au/30350/.
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Concern regarding the health effects of indoor air quality has grown in recent years, due to the increased prevalence of many diseases, as well as the fact that many people now spend most of their time indoors. While numerous studies have reported on the dynamics of aerosols indoors, the dynamics of bioaerosols in indoor environments are still poorly understood and very few studies have focused on fungal spore dynamics in indoor environments. Consequently, this work investigated the dynamics of fungal spores in indoor air, including fungal spore release and deposition, as well as investigating the mechanisms involved in the fungal spore fragmentation process. In relation to the investigation of fungal spore dynamics, it was found that the deposition rates of the bioaerosols (fungal propagules) were in the same range as the deposition rates of nonbiological particles and that they were a function of their aerodynamic diameters. It was also found that fungal particle deposition rates increased with increasing ventilation rates. These results (which are reported for the first time) are important for developing an understanding of the dynamics of fungal spores in the air. In relation to the process of fungal spore fragmentation, important information was generated concerning the airborne dynamics of the spores, as well as the part/s of the fungi which undergo fragmentation. The results obtained from these investigations into the dynamics of fungal propagules in indoor air significantly advance knowledge about the fate of fungal propagules in indoor air, as well as their deposition in the respiratory tract. The need to develop an advanced, real-time method for monitoring bioaerosols has become increasingly important in recent years, particularly as a result of the increased threat from biological weapons and bioterrorism. However, to date, the Ultraviolet Aerodynamic Particle Sizer (UVAPS, Model 3312, TSI, St Paul, MN) is the only commercially available instrument capable of monitoring and measuring viable airborne micro-organisms in real-time. Therefore (for the first time), this work also investigated the ability of the UVAPS to measure and characterise fungal spores in indoor air. The UVAPS was found to be sufficiently sensitive for detecting and measuring fungal propagules. Based on fungal spore size distributions, together with fluorescent percentages and intensities, it was also found to be capable of discriminating between two fungal spore species, under controlled laboratory conditions. In the field, however, it would not be possible to use the UVAPS to differentiate between different fungal spore species because the different micro-organisms present in the air may not only vary in age, but may have also been subjected to different environmental conditions. In addition, while the real-time UVAPS was found to be a good tool for the investigation of fungal particles under controlled conditions, it was not found to be selective for bioaerosols only (as per design specifications). In conclusion, the UVAPS is not recommended for use in the direct measurement of airborne viable bioaerosols in the field, including fungal particles, and further investigations into the nature of the micro-organisms, the UVAPS itself and/or its use in conjunction with other conventional biosamplers, are necessary in order to obtain more realistic results. Overall, the results obtained from this work on airborne fungal particle dynamics will contribute towards improving the detection capabilities of the UVAPS, so that it is capable of selectively monitoring and measuring bioaerosols, for which it was originally designed. This work will assist in finding and/or improving other technologies capable of the real-time monitoring of bioaerosols. The knowledge obtained from this work will also be of benefit in various other bioaerosol applications, such as understanding the transport of bioaerosols indoors.
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Alhakim, Ali, and Roz Hakim. "Inneklimat i kontorsmiljö : Utvärdering av inneklimat i en kontorsmiljö med fokus på ventilationen." Thesis, KTH, Byggteknik och design, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231499.
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I dagens samhälle tillbringar människan ca 90 procent av sin tid inomhus, vilket innebär att människan befinner sig i konstgjort inomhusklimat. Då människan tenderar att befinna sig inomhus är det stor vikt att ventilationen ska fungera så bra som möjligt och att inomhusklimatet är tillfredsställande för vårt välmående och välbefinnande på arbetsplatsen. Tidigare studier visar att nästan hälften av svenskar är missnöjda med ventilationen i deras arbetsmiljö (kontor). Ett bra inomhusklimat i kontorsmiljöer ökar tillfredställandet hos personalen, ökar produktiviteten samt minskar sjukfrånvaron. Detta leder till att organisationen/företaget besparar pengar i slutändan, då personalen arbetar mer effektivt och har mindre sjukfrånvaro. Syftet med denna studie är att undersöka klimatet i kontorsmiljön med fokus på termisk komfort samt se hur ventilation systemen påverkar inomhusklimatet. Vidare kommer sambanden mellan dessa att analyseras. Målet är undersöka hur komforten på kontoret påverkar människors hälsa, produktivitet och välmående. Målet är även att identifiera om det råder bristfällig ventilation samt att presentera eventuella förbättringar. I studien genomförs en undersökning av sex kontor på Brinellvägen 23. I undersökningen tillämpas en enkätstudie och ett antal olika mätningar, flödesmätningar, koldioxidsmätningar, temperaturmätningar och den relativa fuktigheten. I flödesmätningarna mäts till – och frånluften på samtliga kontor. Medan koldioxidmätningarna mäter även temperaturen och relativa fuktigheten. Koldioxidsmätningarna pågick i två timmar i 4 kontor, medan i de två resterande kontoren fortsatte mätningarna under en hel arbetsdag. Enkätstudien tilldelades ut till personalen i kontoren i syfte att ta del av subjektiva åsikter kring miljön i kontoren. Resultaten från mätningarna och enkätundersökningen visar att klimatet i kontoren i överlag inte var tillfredställande och obehag upplevdes utav personerna som arbetar där. Endast ett kontor uppfyllde det projekterade tilluftsflödet, medan de resterande kontoren varken uppfyllde projekterade flödena eller BBR:s krav för mängden flöde i kontorsmiljöer. Koldioxidhalten i kontoren med en person klarade av gränsen under 1000 ppm. Dock är kontoren projekterade för två personer och när två personer arbetade i kontoren översteg koldioxidhalten till ca 1200 ppm. Då koldioxidhalten överstiger 1000 ppm bör ventilationen kontrolleras, vilket behövs i detta fall.In today's society, humans spend about 90 percent of their time indoors, in an artificial indoor climate. As people tend to be indoors more and more, it is important that the ventilation work as well and efficiently as possible, and that the indoor climate is pleasing for our well-being at the workplace. Previous studies show that almost half of Swedes are dissatisfied with the ventilation in their work environment (offices). A good indoor climate in offices increases employee satisfaction, increases productivity, and reduces absenteeism. This causes the organization / company to save money in the end, as staff work more efficiently and have less sick leave. The purpose of this study is to investigate the climate in office environment, focusing on thermal comfort and to see how ventilation systems affect the indoor climate. Furthermore, the relationships between these will be analyzed. The aim is to investigate how the comfort in the office affects human health, productivity and well-being. The goal is also to identify if there is insufficient ventilation to the offices that will be investigated and to eventually present possible improvements. In this report a study of six offices on Brinellvägen 23 was carried out. In the study, a number of flow measurements are carried out for each office's supply and exhaust air, carbon dioxide measurements, temperature and the relative humidity for four hours in four of the offices, with open and closed doors. While in two of the offices, the measurements continued for a whole working day, 6-8h. In addition to these measurements, surveys were distributed to the staff in the offices in order to share subjective opinions about the environment in the offices. The results from the measurements and the survey showed that the overall climate was not satisfactory, and discomfort was experienced by the people working there. Only one office met the projected supply airflow, while the remaining offices neither met the projected flows nor BBR requirements for the amount of flow in office environments. The carbon dioxide levels in the offices with one person was acceptable, they did not pass the limit of 1000 ppm. However, the offices were projected for two persons and when two persons worked in the offices, the carbon dioxide levels exceeded about 1200 ppm. When the carbon dioxide level exceeds 1000 ppm, it is recommended that the ventilation be checked, as needed in this case.
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Gaidžiūnaitė, Daiva. "Oro srauto pasiskirstymo pagrindiniame ortakyje tyrimai." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110602_114712-40431.
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Darbo apimtis 42 puslapiai, jame yra 15 paveikslų ir 2 lentelės. Literatūros sąraše 31 šaltiniai(iš jų 11 rusų kalba). Darbo pradžia 2009.09.01 pabaiga 2011.05. Šio darbo tikslas – nustatyti debito koeficiento kitimą išilgai pagrindinio ortakio, priklausomai nuo šoninių ortakių aerodinaminio pasipriešinimo ir tiekiamo oro srauto. Ekspermentinio stendo pagalba nustatyti faktinis oro pasiskirstymas išilgai pagrindinio ortakio. Matematinio modulio pagalba apskaičiuotas teorinis oro pasiskirstymas, kai oras išteka į šoninius ortakius veikiamas statinio slėgio. Išanalizavus rezultatus nustatytas debito koeficiento kitimas išilgai skirstomojo ortakio ir jį įtakojantys veiksniai.The volume of work contains 42 pages, 15 pictures and 2 tables. In the literature list 31 are sources (of them 11 are russian). The beginning of work – 2009.09.01 and the end – 2011.05. The aim of this paper is to define the variation of yield coefficient along the main channel, depending on the aerodynamic resistance of lateral duct and the flow of the supplied air. With the help of the experimental stand, to define real dissemination of air along the main channel. With the help of the mathematic module, to calculate theoretical dissemination of air, when it flows to lateral duct affected by static pressure. After the analysis of the results, the variation of yield coefficient along the main channel and the influencing factors were defined.
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Yin, Youbing. "MDCT-based dynamic, subject-specific lung models via image registration for CFD-based interrogation of regional lung function." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1112.
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Computational fluid dynamics (CFD) has become an attractive tool in understanding the characteristic of air flow in the human lungs. Inter-subject variations make subject-specific simulations essential for understanding structure-function relationship, assessing lung function and improving drug delivery. However, currently the subject-specific CFD analysis remains challenging due, in large part to, two issues: construction of realistic deforming airway geometry and imposition of physiological boundary conditions. To address these two issues, we develop subject-specific, dynamic lung models by utilizing two or multiple volume multi-detector row computed tomography (MDCT) data sets and image registrations in this thesis. A mass-preserving nonrigid image registration algorithm is first proposed to match a pair of three-dimensional (3D) MDCT data sets with large deformations. A novel similarity criterion, the sum of squared tissue volume difference (SSTVD), is introduced to account for changes in intensity with lung inflation. We then demonstrate the ability to develop dynamic lung models by using a pair of lung volumes to account for deformations of airway geometries and subject-specific boundary conditions. The deformation of the airway geometry is derived by the registration-derived deformation field and subject-specific boundary condition is estimated from regional ventilation in a 3D and one-dimensional (1D) coupled multi-scale framework. Improved dynamic lung models are then proposed from three lung volumes by utilizing nonlinear interpolations. The improved lung models account for nonlinear geometry motions and time-varying boundary conditions during breathing. The capability of the proposed dynamic lung model is expected to move the CFD-based interrogation of lung function to the next plateau.
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Urban, Ondřej. "Větrání tělocvičny." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372264.
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The master thesis deals with flow modeling in the CFD program. By means of which the opti-mal version of the air distribution diffuser in the sports hall will be selected. The first variant will bring fresh air through textile diffusers. The second variant will bring fresh air through flooded large circular diffusers. The tested parameter of the indoor environment will be the flow velocity and the age of the air. The better-performing version will be processed as an implementation documentation.
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Olausson, Jesper. "Energy efficiency in a renovated modern office with activity-based work style." Thesis, Högskolan i Gävle, Energisystem och byggnadsteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-30113.
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During renovation Ljusåret 2 was converted to a modern office with an activity based work style (ABW) with a Demand Controlled Volume (DCV) ventilation system connected to a closed-loop duct. Cooling is provided through air handling units and active water based beams, the underfloor heating system was kept. Written instruction and specification have been studied for the two different control systems Schneider EcoStructure and Lindinspect. Both control systems have been analyzed according to time schedule, set-point and process value by using different functions in software. To be able to perform a energy audit and look at indoor climate for Ljusåret 2 there have been studies according to underfloor heating, constructions of ventilation system, diversity factor for DCV, closed-loop-ducts, heat losses from ducts, cooling demand and energy certification. According to this audit, energy performance is calculated to 89.1 kWh/m2 according to building energy, activity energy is not audited or calculated. During design phase, an energy calculation was made by an energy consultant with the result of 81.3 kWh/m2. The estimated performance is a 9.6 % increase. This building is designed for Miljöbyggnad certification of level silver and should be ≤ 109 kWh/m2,year. According to audit and calculation for energy performance this level is possible to keep. The estimated energy performance have been calculated with only 4 month of statistics from January until April 2019 because Ljusåret 2 have just been renovated. District heating has been estimated through the energy signature by data from energy meter. Electrical components for the building have been measured and energy usage calculated. Energy produced by compression chiller have been estimated with calculated performance from design phase and adding heat transfer between rooms and supply ducts. Energy between rooms and supply ducts were not included in energy calculation during the design phase. According to the control system for the DCV system there have been some issues with high temperature in supply ducts even when they are supplied with 15 ºC from air- handling unit. There have been measurement to the ventilation system 5701-5704 that is connected to a close-loop duct with a result of temperatures between 15.2 ºC up to 21.4 ºC and the velocity has varied between 0.05-2.1 m/s in different measurement spots. This is an increase of 6.4 ºC. A heat transfer calculation have been made in Paroc Calculus to estimate heat transfer between room and supply ducts. The results of this calculation indicates the same level of temperature increases as when the system was measured. With no thermal insulation cooling capacity is lost to half after less than 5 m with a velocity of 0.2 m/s, after 15 m with a velocity of 1 m/s and 30 m with a velocity of 2 m/s . This should be compared with supply duct with 20 mm of thermal insulation that has lost its cooling capacity after less than 13 m with a velocity of 0.2 m/s, after 63 m with a velocity of 1 m/s and is increase with 4 ºC after 100 m with a velocity of 2 m/s. Using closed-loop ducts with velocity below 2.0 m/s and without thermal insulation combined with under tempered supply air is not a good combination. Even short length with low velocity and lack of thermal insulation is devastating because of heat transfer according to logarithmical temperature difference between room and supply ducts. A closed-loop duct is often designed as a pressure chamber and recommended when using DCV and/or VAV ventilation to avoid problems with noise and to be able to reduce the need of dampers. Problems with temperature increasing according to velocity in ducts must be taken in consideration. For Ljusåret 2 this will affect district heating usage where ducts are placed because underfloor heating must compensate heat transfer. Chilled water must be provided an extra time for rooms with both DCV and chilled beams and rooms with only DCV is less comfortable which they could been with a correct installation.
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Lapáček, Milan. "Čištění vzduchotechnických systémů a dosažitelné energetické úspory." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232143.
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The main aim of this thesis is to explore fouling of air ducts and its influence on energy consumption of HVAC systems. The first part focuses on typical parts that create the IAQ in buildings and on evaluating energy consumption of air transportation. The following section deals with the theories of fluid flow, flow regimes and pressure losses that are created as a side effect. The thesis outlines possible methods of assessing the impact of pollution with an emphasis on pressure losses and their influence on the fan power consumption. The actual experimental measurement, conducted in a selected industrial plant, is focused on an influence of cleanness of textile diffuser on HVAC device power consumption. For the further research of this process, measuring equipment with suitable measurement method is designed and constructed.
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Romero, João Vitor Fontenele. "Estudo experimental de sonda direcional para determinação da velocidade do escoamento de ar." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-19072011-104247/.
Full textAbstract:
O presente trabalho trata do desenvolvimento de uma sonda de pressão para medição de magnitude e direção da velocidade em um escoamento de ar. Primeiramente, é feita uma pesquisa sobre métodos e instrumentos de medição de velocidade de escoamentos de ar, utilizando a literatura existente sobre os tipos de medidores e suas restrições e capacidades na medição de direção do escoamento. Em seguida, são escolhidos dois tipos de medidores capazes de atender aos requisitos de fabricação simples e robusta, sendo um deles aplicado a escoamentos bidimensionais (sensor de três orifícios, tipo prisma) e o outro, a escoamentos tridimensionais (sensor de cinco orifícios, tipo pirâmide). É feito o projeto detalhado destes medidores e define-se o método de fabricação dos mesmos, comparando o método da prototipagem rápida com a usinagem. Uma vez fabricados os sensores, são realizados ensaios de caráter investigativo para mensurar a faixa de ângulos de medição de cada sensor. De posse dos resultados, é feito um estudo sobre os coeficientes adimensionais utilizados para a definição do ângulo de escoamento a partir das medições de pressão realizadas pelo sensor. É proposto um novo conjunto de coeficientes adimensionais com os quais se determina uma faixa de medição de ângulos entre -25 e + 25 para a sonda tipo prisma e uma faixa entre -35 e + 35 para a sonda tipo pirâmide. Finalmente, são feitas as curvas de calibração para os sensores e se discute sobre suas aplicações na medição de velocidade de escoamentos de ar.The present work deals with the development of a pressure probe for measuring magnitude and direction of velocity from an air flow. Initially, it is made a review of methods and instruments to measure air flow velocity, using the existing literature on kinds of instruments with their restrictions and capabilities on flow direction measurement. Secondly, two kinds of sensors are chosen based on the requirements of easy and robust manufacturing, being one of them applied to bi-dimensional flows (three-hole probe, prism type) and the other one for tri-dimensional flows (five-hole probe, pyramid type). The detailed design of these probes is made and the fabrication method is chosen comparing the fast prototyping method with machining. Once these sensors are manufactured, investigative tests are carried out in order to measure the flow angle range for each sensor. With these results, a study is made on the non-dimensional coefficients used for definition of flow angle from the pressure measurements from the sensor. A new set of non-dimensional coefficients is proposed and a flow angle range between -25 and + 25 is determined for the prism probe and a range between -35 and + 35 for the pyramid probe, Finally, the calibration curves are made for the two sensors, followed by a discussion on the applications on air flow velocity measurements.