Thesis (M.S.)--Oregon Graduate Center, 1977.

No description available.

Thermal environment control of chilled food manufacturing facilities plays a critical role in maintaining the required food product temperature during processing to ensure food quality and maximise shelf life. The provision of cooling to maintain the required temperatures in the processing halls, which should be in the range between 4 °C and 12°C also impacts on energy consumption and CO2 emissions. Chilled food manufacturing facilities normally have high ceilings to provide flexibility in their use and accommodate different height equipment. In these facilities cooling is commonly provided by fan coil units installed at ceiling level that recirculate air in the space through the cooling coils with high velocities. Small amounts of fresh air can also be provided to the space through a separate fresh air system. The low temperatures and high velocity of air circulating in the space lead to uncomfortable environments for the workers and high energy consumption. Refrigeration systems in chilled food manufacturing facilities account for more than 60% of the energy consumption in the plant so identifying ways of improving the thermal environment in these facilities and reducing energy consumption can lead to increased productivity and profitability of chilled food operations. This thesis makes a contribution to this challenge by investigating alternative air distribution approaches for both existing and new facilities. A primary consideration was to identify solutions that could be easily retrofitted to existing cooling systems in the space at low cost and minimum disruption to the production. The research involved the investigation of two chilled food manufacturing spaces with different cooling system arrangements to establish their performance characteristics and ability to provide the required conditions of temperature and velocities at low level in the space to minimise thermal discomfort. Learnings from these investigations were used to develop in the laboratory a test facility that could reproduce chilled food manufacturing environments at a smaller scale and enable the investigation of different cooling systems and air distribution arrangements. CFD models were also developed and validated against temperature and air velocity data from the chilled food spaces in the factories and the test facility. The models were then used to evaluate different chilled air distribution designs prior to them being manufactured and installed for evaluation in the test facility. The main objective was to achieve temperature stratification and low air velocities at low levels in the space. Key findings and contribution to knowledge for science and technology of cold processing areas are the follow: i) The monitoring of the two case studies provided evidence of the air-temperature distribution issues in existing chilled food facilities such as high velocities, poor temperature distribution, cooling of the whole space and increased energy consumption. ii) Numerical and experimental results of this research provided guidelines of how air distribution solutions in existing chilled food facilities can be improved regarding their air temperature efficacy and energy efficiency. For example, supplying air from evaporator coils at medium level with circular or semi-circular fabric ducts as air distribution solutions, could achieve temperature stratification in the space with lower temperatures at low level covering the manufacturing area and higher temperatures towards the ceiling; In addition, medium level air supply with fabric duct was shown to provide in the region of 9% reduction in energy consumption compared to high level supply with the same duct; Furthermore, medium level air supply with a fabric duct provided 23% energy savings compared to air supply with an un-ducted fan-coil system which is the most common air distribution method in chilled food factories; iii) Numerical and experimental results derived guidelines of which air distribution systems should be avoided in new chilled food facilities. Tests and CFD modelling comparing air distribution with circular fabric duct and metal duct with linear diffusers showed that the circular fabric duct provided a better thermal environment in terms of temperature uniformity and low air velocities; Furthermore, comparing the air flow velocities obtained from the air distribution system via non-ducted coil and fabric ducts as air distribution solutions, it can be highlighted that the fabric duct provided much lower air flow velocities. This is beneficial to achieve some temperature stratification in the space and reduce the discomfort of the workers produced by high velocities as seen in the case of the non-ducted coil. iv) A simulation tool developed that couples refrigeration system and CFD modelling has been shown to be able to simulate the dynamics of air distribution and refrigeration system energy consumption in chilled food spaces. The tool can be used to optimise the design of air distribution systems from both thermal environment and energy consumption perspectives.

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.

Allmänna bad bidrar i hög grad till att främja allmänhetens hälsa och välbefinnande. De erbjuder möjlighet till motion och rekreation för människor i alla åldrar. För att badgäster ska trivas och må bra krävs det att vatten- och luftkvalitet håller hög nivå. I syfte att förhindra spridning av sjukdomsalstrande organismer mellan badgäster används klor som en central komponent för att desinficera vattnet. Kloret lämnar dock restprodukter efter sig, främst trikloramin som påverkar människors hälsa negativt. Trikloramin samlas över vattenytan och stannar kvar i andningszonen om inte föroreningarna transporteras bort via luftrörelser.I Nolhaga simhall sker fram till 2018 en ombyggnad av anläggningen. Rapporten berör den nya ventilationslösning som kommer att användas till motionsbassängen. För att studera hur denna lösning fungerar och hur god luftväxling den skapar över vattenytan har en modell av simhallen skapats i CAD-program. Luftflöden har sedan simulerats i en förenklad CFD modellen och jämförts med ett röktest i en liknande simhall. Utöver den lösning som är tänkt att byggas har ett alternativ med kompletterande frånluftsdon i golvnivå simulerats.Resultatet indikerar att lufthastigheter över vattenytan ligger inom de rekommendationer som finns angivna. Luften har en tendens att röra sig i lokalen med ett återcirkulerande beteende där tilluften följer taket in i hallen för att sedan gå ner vid bakre väggen och tillbaka över vattenytan. Luftrörelserna följer detta beteende oberoende om frånluftsdonet är placerat i golv- eller taknivå. Någon skillnad i mängd bortfört trikloramin kan inte säkerställas med de metoder som använts i rapporten. Röktestet gav inte ett tillräckligt tydligt resultat för att några kopplingar till simulering ska kunna göras.Brist på tid, förkunskaper och erfarenhet inom området gör att osäkerheten kring de resultat som nåtts är stor. Mer arbete inom CFD och badhusventilation krävs för att öka trovärdigheten. / Public baths contributes significantly to the promotion of public health and wellbeing. To be able to supply a pleasant experience for bathers, a high quality of water and air is required. To avoid spreading of pathogens between bathers, Chlorine is used as a central component for disinfecting the water. Chlorine residues such as Trichloramine affect human health and are concentrated above the water surface and will remain in the breathing zone unless the pollution is carried away by air movement.Nolhaga public bath is undergoing a renovation and this report is a study of the new ventilation system which has been installed. To investigate the air flow pattern in the hall a CAD model of the space was created. CFD software was used to simulate airflow in the model. Results have also been compared with a smoke test, performed in a similar building. In addition to the suggested solution a different approach, with additional exhaust air vents placed at floor level, has been tested.The results show that the air speeds over the water surface are within the given recommendations. The air has a tendency to move around in the room with a recirculating behaviour where the supply air follows the roof to the back wall and then returns over the surface of the water. This kind of behaviour might be beneficial for removing Trichloramines if exhaust air vents are placed near the air supply units. This method uses the air movement to remove pollutants where the concentration is highest and removes them from the building. Performed smoke test gave only vague indications that the simulation results can be linked to actual air movement due to the small amount of information it provided.Due to the lack of time, knowledge and experience in the field, the uncertainty of the achieved results is great. Additional work in CFD and ventilation of public baths is required to enhance credibility of results.

A well-functioning, energy-efficient ventilation system is of vital importance to offices, not only to provide the kind of comfortable, healthy indoor environment necessary for the well-being and productive work performance of occupants, but also to reduce energy use in buildings and the associated impact of CO2 emissions on the environment. To achieve these goals impinging jet ventilation has been developed as an innovative ventilation concept. In an impinging jet ventilation system, a high momentum of air jet is discharged downwards, strikes the floor and spreads over it, thus distributing the fresh air along the floor in the form of a very thin shear layer. This system retains advantages of mixing and stratification from conventional air distribution methods, while capable of overcoming their shortcomings. The aim of this thesis is to reach a thorough understanding of impinging jet ventilation for providing a good thermal environment for an office, by using Computational Fluid Dynamics (CFD) supported by detailed measurements. The full-field measurements were carried out in two test rooms located in a large enclosure giving relatively stable climate conditions. This study has been divided into three parts where the first focuses on validation of numerical investigations against measurements, the second addresses impacts of a number of design parameters on the impinging jet flow field and thermal comfort level, and the third compares ventilation performance of the impinging jet supply device with other air supply devices intended for mixing, wall confluent jets and displacement ventilation, under specific room conditions. In the first part, velocity and temperature distributions of the impinging jet flow field predicted by different turbulence models are compared with detailed measurements. Results from the non-isothermal validation studies show that the accuracy of the simulation results is to a great extent dependent on the complexity of the turbulence models, due to complicated flow phenomena related to jet impingement, such as recirculation, curvature and instability. The v2-f turbulence model shows the best performance with measurements, which is slightly better than the SST k-ω model but much better than the RNG k-ε model. The difference is assumed to be essentially related to the magnitude of turbulent kinetic energy predicted in the vicinity of the stagnation region. Results from the isothermal study show that both the SST k-ω and RNG k-ε models predict similar wall jet behaviours of the impinging jet flow. In the second part, three sets of parametric studies were carried out by using validated CFD models. The first parametric study shows that the geometry of the air supply system has the most significant impact on the flow field. The rectangular air supply device, especially the one with larger aspect ratio, provides a longer penetration distance to the room, which is suitable for industrial ventilation. The second study reveals that the interaction effect of cooling ceiling, heat sources and impinging jet ventilation results in complex flow phenomena but with a notable feature of air circulation, which consequently decreases thermal stratification in the room and increases draught discomfort at the foot level. The third study demonstrates the advantage of using response surface methodology to study simultaneous effects on changes in four parameters, i.e. shape of air supply device, jet discharge height, supply airflow rate and supply air temperature. Analysis of the flow field reveals that at a low discharge height, the shape of air supply device has a major impact on the flow pattern in the vicinity of the supply device. Correlations between the studied parameters and local thermal discomfort indices were derived. Supply airflow rates and temperatures are shown to be the most important parameter for draught and stratification discomfort, respectively. In the third part, the impinging jet supply device was shown to provide a better overall performance than other air supply devices used for mixing, wall confluent jets and displacement ventilation, with respect to thermal comfort, heat removal effectiveness, air exchange efficiency and energy-saving potential related to fan power.

Orientadores: Luis Augusto Barbosa Cortez, Clement Vigneault / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-04T00:29:08Z (GMT). No. of bitstreams: 1 Castro_LarissaRodriguesde_D.pdf: 2524603 bytes, checksum: 96c23f390f533440db271887126eb814 (MD5) Previous issue date: 2004 / Resumo: Esta pesquisa teve como objetivo desenvolver uma metodologia para o projeto dos orifícios de embalagens para frutas e hortaliças submetidas ao processo de resfriamento rápido a ar forçado. Tendo em vista as altas perdas registradas anualmente sobretudo devido à falta de embalagens adequadas e armazenagem frigorificada, tal metodologia poderá auxiliar de forma prática e precisa a escolha da configuração dos orifícios da embalagem para maximização da eficiência do resfriamento rápido de produtos hortícolas. Esta ferramenta deverá ser utilizada em combinação com demais tecnologias existentes para o projeto de uma embalagem suficientemente atrativa ao consumidor e que atenda não apenas às necessidades do produto submetido a tratamentos pós-colheita, como também à resistência estrutural da caixa, possibilitando inclusive sua higienização, reutilização e desmontagem, visando reduzir custos de confecção e transporte. Para atingir a meta da pesquisa, os produtos hortícolas acondicionados em embalagens foram representados por produtos-modelo nos experimentos laboratoriais. Vários materiais e arranjos experimentais foram testados até se chegar à simulação de uma embalagem com um grupo de esferas plásticas sólidas instrumentadas. Estas simularam com maior precisão a distribuição do ar através de um leito de produtos hortícolas durante o resfriamento rápido a ar forçado. A partir dos resultados obtidos para o coeficiente de resfriamento das esferas, foram desenvolvidas correlações para determinação indireta da velocidade de aproximação do ar ao redor de cada uma delas, considerando sua posição na embalagem relativa ao ar de entrada. Estas correlações foram posteriormente aprimoradas através do refinamento da pesquisa na faixa de regime de fluxo transiente. A precisão das correlações estabelecidas foi verificada através de análises de balanço de massa nas camadas de produto ao longo da direção do fluxo de ar. A metodologia foi aplicada para a investigação do efeito de diferentes configurações de abertura de embalagem na distribuição do ar através do produto submetido ao resfriamento. Tais configurações incluíram orifícios centrais, periféricos, diagonais e uniformemente distribuídos, além das aberturas tipo ¿alça¿ para manuseio. Também foi realizada uma análise energética envolvendo o calor adicionado ao sistema devido à taxa respiratória do produto e ao funcionamento do ventilador usado no resfriamento rápido. Através da ferramenta desenvolvida, foram definidos certos valores de operação do sistema para maximizar a eficiência do processo de resfriamento, em termos de velocidade e uniformidade de resfriamento e energia requerida, que afetarão a qualidade e preço finais do produto. Assim, recomenda-se o projeto de orifícios uniformemente distribuídos na superfície da embalagem com área total aberta entre 8 e 16% . A porcentagem a ser escolhida nesta faixa dependerá dos limites de resistência estrutural do material, fluxo de ar fornecido pelo ventilador e taxa respiratória do produto. Por exemplo, hortícolas com atividade metabólica muito elevada, como brócolis, acondicionados em caixas mais abertas exigirão um maior fluxo de ar para otimização do processo de resfriamento rápido / Abstract: The aim of this research was to develop a methodology for designing container openings for fruits and vegetables submitted to a forced-air precooling process. Due to significant annual losses of fruits and vegetables, especially because of inappropriate packaging and storage, this tool could allow practical and accurate selection of the best package opening configuration to maximize the precooling efficiency of horticultural produce. The tool should be combined with other technologies currently in market use to design a container sufficiently attractive to consumers. This container must not only meet the produce requirements when submitted to postharvest operations, but also the material structural constraints. Furthermore, reusable and foldable containers could be desirable for manufacture and transport cost reductions. To this end, packed horticultural produce were represented by produce simulators in the trials. Several materials and experimental set-ups were tested before selecting an arrangement of instrumented solid plastic spheres in a container. These spheres simulated the air distribution through a horticultural produce stack during forced-air precooling with more accuracy. Correlations were established by measuring the cooling rate of the instrumented simulators for indirect determination of the surrounding air velocity, as a function of the simulator locations in reference to the inlet air. These correlations were further improved by refining the airflow range studied in laminar, transient, and turbulent phases. Their applicability was verified by performing a mass balance through the produce layers perpendicular to the main airflow direction. The methodology was applied to investigate the container opening design on air distribution through horticultural produce submitted to precooling. The configurations tested included central, peripheral, diagonal, and uniformly distributed openings, besides the container handle openings. Furthermore, an energy analysis was performed involving heat added to the system due to produce respiratory rate and fan functioning during precooling. The research tool developed here allowed defining some optimum values for system operation to maximize the cooling efficiency regarding the process rate and uniformity and required energy, which affect produce final quality and cost. Therefore, it is recommended that design openings be uniformly distributed on package surface with total vented area between 8 and 16%. The exact percentage to be selected in this range will depend on the material structural resistance, airflow and produce respiratory rates. For instance, horticultural produce with very high respiratory activity, such as broccoli, require higher airflow rate when submitted to larger venting package to optimize precooling process / Doutorado / Tecnologia Pós-Colheita / Doutor em Engenharia Agrícola

This thesis deals with measuring of the distribution and volume of intake air inside vehicle cockpit under varying outdoor conditions and air conditioning settings. Fan characteristic was developed to determine the volume of air taken inside the cockpit. The measuring was made using speed probes in climatic chamber, where different outdoor conditions could be simulated. Following the measurements there is dependence between the air distribution and the outside temperature. The diploma thesis presents source materials to develop a mathematical model of car cabin.

O sistema de ventilação por mistura (MV), utilizado atualmente em cabines de aeronaves na distribuição do ar tratado, não tem propiciado condições adequadas de conforto térmico e pode, devido às suas características de mistura, propagar rapidamente doenças infecciosas na cabine. Sistemas de ventilação utilizados em ambientes de edificações, como o sistema de distribuição de ar por deslocamento (DV) e o sistema de distribuição de ar pelo piso (UFAD) e variantes destes sistemas, estão começando a ser propostos. Função disto, o presente trabalho comparou três arquiteturas de distribuição de ar: o sistema tradicional (MV), o sistema de insuflamento de ar pelo piso (UFAD) e uma variação do sistema UFAD, incluindo insuflamento lateral abaixo dos bagageiros, denominado de UFAD modificado. Os ensaios foram realizados em cabine de mock up de aeronave com 12 lugares, ocupados por manequins aquecidos simulando os passageiros, considerando duas temperaturas para o ar insuflado na cabine: 18°C e 22°C. Os resultados mostram influência significativa da temperatura de insuflamento do ar nas condições de desconforto térmico local, juntamente com resultados promissores para o sistema UFAD, com percentuais de desconforto devido às correntes de ar menores que 20%, com exceção da região de insuflamento do ar no corredor. / Mixing ventilation system (MV), currently used in aircraft cabins for treated air distribution, has not provided adequate conditions for thermal comfort and may, due to its mixing characteristics, spread quickly infectious diseases in the cabin. Ventilation systems used in buildings environments, such as displacement ventilation system (DV) and underfloor air distribution system (UFAD) and variants of these systems are beginning to be proposed. Due to that, the present study compared three air distribution architectures: the traditional system (MV), underfloor air distribution system (UFAD) and a variation of the UFAD system, including side air supply under bins, called UFAD modified. Tests were performed in aircraft cabin mock up with 12 seats, occupied by heated manikins simulating passengers, considering two air supply temperatures into the cabin: 18°C and 22°C. Results show significant influence of air supply temperature in conditions of local thermal discomfort, together with promising results for UFAD system, with percentages of discomfort due to draught less than 20%, except in the air insufflation area in aisle.

O sistema de ventilação por mistura (MV), utilizado atualmente em cabines de aeronaves na distribuição do ar tratado, não tem propiciado condições adequadas de conforto térmico e pode, devido às suas características de mistura, propagar rapidamente doenças infecciosas na cabine. Sistemas de ventilação utilizados em ambientes de edificações, como o sistema de distribuição de ar por deslocamento (DV) e o sistema de distribuição de ar pelo piso (UFAD) e variantes destes sistemas, estão começando a ser propostos. Função disto, o presente trabalho comparou três arquiteturas de distribuição de ar: o sistema tradicional (MV), o sistema de insuflamento de ar pelo piso (UFAD) e uma variação do sistema UFAD, incluindo insuflamento lateral abaixo dos bagageiros, denominado de UFAD modificado. Os ensaios foram realizados em cabine de mock up de aeronave com 12 lugares, ocupados por manequins aquecidos simulando os passageiros, considerando duas temperaturas para o ar insuflado na cabine: 18°C e 22°C. Os resultados mostram influência significativa da temperatura de insuflamento do ar nas condições de desconforto térmico local, juntamente com resultados promissores para o sistema UFAD, com percentuais de desconforto devido às correntes de ar menores que 20%, com exceção da região de insuflamento do ar no corredor. / Mixing ventilation system (MV), currently used in aircraft cabins for treated air distribution, has not provided adequate conditions for thermal comfort and may, due to its mixing characteristics, spread quickly infectious diseases in the cabin. Ventilation systems used in buildings environments, such as displacement ventilation system (DV) and underfloor air distribution system (UFAD) and variants of these systems are beginning to be proposed. Due to that, the present study compared three air distribution architectures: the traditional system (MV), underfloor air distribution system (UFAD) and a variation of the UFAD system, including side air supply under bins, called UFAD modified. Tests were performed in aircraft cabin mock up with 12 seats, occupied by heated manikins simulating passengers, considering two air supply temperatures into the cabin: 18°C and 22°C. Results show significant influence of air supply temperature in conditions of local thermal discomfort, together with promising results for UFAD system, with percentages of discomfort due to draught less than 20%, except in the air insufflation area in aisle.