Submitted in fulfilment of the requirements of the egree of Master of Technology: Chemical Engineering, Durban University of Technology, 2011. / The South African electroplating industry generates large volumes of hazardous waste water that has to be treated prior to disposal. The main source of this waste water has been the rinse system. Conventional end-ofpipe waste water treatment technologies do not meet municipality standards. The use of technologies such as membranes, reverse osmosis and ion exchange are impractical, mainly due to their cost and technical requirements. This study identified source point reduction technologies, close circuiting of the electroplating process, specific to the rinse system as a key development. Specifically the application of a low flow counter current rinse system for the recovery of the rinse water in the plating bath was selected. However, the recovery of the rinse tank water was impeded by the low rates of evaporation from the plating bath, which was especially prevalent in the low temperature operating plating baths. This master’s study proposes the use of an induced draft evaporative cooling tower for facilitation of evaporation in the plating bath. For total recovery of the rinse tank water, the rate of evaporation from the plating bath has to be equivalent to the rinse tanks make up water requirements. A closed circuit plating system mathematical model was developed for the determination of the mass evaporated from the plating bath and the cooling tower for a specified time and the equilibrium temperature of the plating bath and the cooling tower. The key criteria in the development of the closed circuit plating system model was the requirement of minimum solution specific data as this information is not readily available. The closed circuit plating system model was categorised into the unsteady state and steady state temperature regions and was developed for the condition of water evaporation only. The closed circuit plating system model was programmed into Matlab and verified. The key factors affecting the performance of the closed circuit plating system were identified as the plating solution composition and operational temperature, ambient air temperature, air flow rate and cooling tower iv packing surface area. Each of these factors was individually and simultaneously varied to determine their sensitivity on the rate of water evaporation and the equilibrium temperature of the plating bath and cooling tower. The results indicated that the upper limit plating solution operational temperature, high air flow rates, low ambient air temperature and large packing surface area provided the greatest water evaporation rates and the largest temperature drop across the height of the cooling tower in the unsteady state temperature region. The final equilibrium temperature of the plating bath and the cooling tower is dependent on the ambient air temperature. The only exception is that at low ambient air temperatures the rate of water evaporation from the steady state temperature region is lower than that at higher ambient air temperatures. Thus the model will enable the electroplater to identify the optimum operating conditions for close circuiting of the electroplating process. It is recommended that the model be validated against practical data either by the construction of a laboratory scale induced draft evaporative cooling tower or by the application of the induced draft evaporative cooling tower in an electroplating facility.

During the last 10 years solar cooling systems attracted more and more interest not only in the research area but also on a private and commercial level. Several demonstration plants have been installed in different European countries and first companies started to commercialise also small scale absorption cooling machines. However, not all of the installed systems operate efficiently and some are, from the primary energy point of view, even worse than conventional systems with a compression chiller. The main reason for this is a poor system design combined with suboptimal control. Often several non optimised components, each separately controlled, are put together to form a ‘cooling system’. To overcome these drawbacks several attempts are made within IEA task 38 (International Energy Agency Solar Heating and Cooling Programme) to improve the system design through optimised design guidelines which are supported by simulation based design tools. Furthermore, guidelines for an optimised control of different systems are developed. In parallel several companies like the SolarNext AG in Rimsting, Germany started the development of solar cooling kits with optimised components and optimised system controllers. To support this process the following contributions are made within the present work: - For the design and dimensioning of solar driven absorption cooling systems a detailed and structured simulation based analysis highlights the main influencing factors on the required solar system size to reach a defined solar fraction on the overall heating energy demand of the chiller. These results offer useful guidelines for an energy and cost efficient system design. - Detailed system simulations of an installed solar cooling system focus on the influence of the system configuration, control strategy and system component control on the overall primary energy efficiency. From the results found a detailed set of clear recommendations for highly energy efficient system configurations and control of solar driven absorption cooling systems is provided. - For optimised control of open desiccant evaporative cooling systems (DEC) an innovative model based system controller is developed and presented. This controller consists of an electricity optimised sequence controller which is assisted by a primary energy optimisation tool. The optimisation tool is based on simplified simulation models and is intended to be operated as an online tool which evaluates continuously the optimum operation mode of the DEC system to ensure high primary energy efficiency of the system. Tests of the controller in the simulation environment showed that compared to a system with energy optimised standard control the innovative model based system controller can further improve the primary energy efficiency by 19 %.

Este trabalho visa comparar experimentalmente a técnica de resfriamento evaporativo e o condicionamento de ar convencional em relação ao índice de umidificação, à redução da temperatura interna do ar e ao consumo energético. O experimento foi realizado em três células de teste submetidas às mesmas condições climáticas, semelhantes em relação às suas características construtivas e ao volume de ar interno. Cada equipamento foi instalado em uma célula, sendo que a célula restante não contou com qualquer sistema de resfriamento, cumprindo, assim, o papel de padrão de referência do comportamento higrotérmico. A técnica de resfriamento evaporativo consiste em um dispositivo eletromecânico de ventilação forçada que insufla o ar para dentro do ambiente, fazendo-o passar por um filtro de celulose umedecido com água corrente. A ventilação forçada espalha gotículas de água no ambiente interno e o contato da água com o ar quente e seco acelera a sua evaporação. Dessa forma, o ar cede calor sensível e as gotículas de água evaporam. Como conseqüência, a temperatura diminui e a umidade do ar aumenta no interior do ambiente. O condicionador de ar convencional, constituído por evaporador, compressor e condensador, refrigera o ar por meio da compressão e da expansão do gás freon. Os dados do interior de cada célula foram automaticamente coletados por meio do Datalogger Campbell Scientific Inc CR10X. As temperaturas de bulbo seco e úmido foram regitradas com sensores termopares tipo T (Cobre-Constantan). A técnica de resfriamento evaporativo atingiu índices adequados de conforto ambiental em períodos de climas quente e seco, demonstrando, assim, ser eficaz em promover a diminuição da temperatura e a umidificação de ambientes internos. Este trabalho sugere, portanto, que a técnica de resfriamento evaporativo pode ser uma alternativa para melhorar as condições térmicas dos espaços de permanência humana com consumo de energia inferior ao do condicionador de ar convencional. / This experimental research aims to compare the evaporative cooling with the conventional air conditioning in terms of levels of humidity, reduction in indoor air temperature, and energy consume. The experiment was conducted in three purpose-built test cells, similar in structure, which were exposed to the same climatic conditions and showed the same indoor air volume rates. Each equipment was installed in one of the test cells, and the remaining cell had no cooling appliances, thus being used as reference standard. The evaporative cooling technique consists of an electrical-mechanical system of forced ventilation which introduces outdoor air into the indoor environment, across a humidifier pad made of cellulose. The forced ventilation spread small drops of water into the indoor environment and the water’s contact with the dry-warm air accelerates the evaporation process. Thus, the air loses sensible heat and the water evaporates. As a result, the air temperature decreases, and the relative humidity increases inside the environment. The conventional air conditioning system, comprises of an evaporator, a compressor and a condenser, cools the air by compressing and expanding Freon gas. The data from each cell was automatically collected by using a Datalogger CR10X. Both dry and wet bulb temperature was measured by using thermocouples type T (Copper-Constantan). The evaporative cooling technique was shown to provide higher levels of human comfort during warm-dry climate, thereby demonstrating that it can be effective in humidifying and constantly replenishing indoor air. This work therefore suggests that the evaporative cooling can be an alternative for improving the conditions of purpose-built environments with lower levels of energy consume when compared with the conventional air-conditioning systems.

With regard to heat stress, the limiting factor inherent in clothing ensembles is the total evaporative resistance. Clothing with higher evaporative resistance impedes the ability to cool by sweat evaporation. Knowing the evaporative resistance provides a means to compare candidate ensembles. Further, a value for evaporative resistance means that a rational method can be used to assess the heat stress exposure. Evaporative resistance of five clothing ensembles (cotton work clothes, cotton coveralls, and three coveralls of particle barrier, liquid barrier and vapor barrier properties) was determined empirically from wear tests during two study phases. For Phase 1, the metabolic rate was held constant at 160 W/m², and three levels of humidity (20, 50, 70% rh) were explored. Fourteen heat-acclimated participants (9 men and 5 women) completed trials for all combinations of clothing ensemble and environment. In the Phase 2 study, the humidity was held constant at 50% rh, and three levels of metabolic rate (114, 176, 250 W/m²) were explored. Fifteen heat-acclimated participants (11 men and 4 women) completed trials for all combinations of clothing ensemble and environment. The data from both phases were analyzed separately using ANOVA. Significant differences were found among ensembles (p<0.0001). The vapor barrier ensemble had the highest resistance at 0.026 kPa m²/W. The liquid barrier was next at 0.018; followed by the particle barrier and cotton coveralls at 0.016. Work clothes was 0.014 kPa m²/W. Vapor and liquid barrier ensembles were found to be significantly different from other ensembles. From the Phase 2 study, evaporative resistances decreased with increased activity and ranged from 0.0024 (cotton coveralls) to 0.0094 (vapor barrier) kPa m²/W. The higher differences were associated with higher total evaporative resistance. The decreased evaporative resistances in Phase 2 can be explained by the pumping action associated with increased work. The relationship of Re,T to the difference of Pair -- Pskin was explored and found Re,T does not remain constant. Environment appeared to influence this relationship.

The research performed in this work investigated evaporative spray cooling systems using water near a 45 degree bends in gas turbine exhaust piping systems. Both experimental data and numerical data were generated with the goal of evaluating the ability of Fluent 6.3.26 to predict the performance of these systems for the purpose of design using only modest computational resources. Three cases were investigated in this research: single phase exhaust flow with no water injection, injecting water before the bend and injecting water after the bend. Various probes were used to measure dry bulb temperature, total pressure and water mass flux of the two phase flow at the exit of the pipe. Seven hole probes and pitot static probes were used to measure single phase flow properties. Numerical simulations were performed using mass flow boundary conditions which were generated from experimental results. A turbulence model was selected for the simulations based on comparisons of single phase simulations with experimental data and convergence ability. Using Fluent’s discrete phase model, different wall boundary conditions for the discrete phase were used in order to find the model which would best match the evaporation rates of the experimental data. Mass flux values through the exit plane of the pipe were found to be the most reliable of all the two phase data collected. Results from numerical simulations revealed the shortcomings of the available discrete phase wall boundary conditions to accurately predict the interaction of the liquid phase with the wall. Experimental results for both cases showed extensive areas of the wall which had liquid film layers running down the length of the pipe. Simulations resulted in particles either failing to impact the wall and create a liquid film, or creating a liquid film which was much smaller than the film present in experimental results. This led to 8% and 15% discrepancy in evaporation amounts between numerical and experimental results for water injection upstream and downstream of the bend respectively. Under-prediction of areas wetted with a wall film in the simulations also led to gross over predictions of wall temperature in numerical results. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2014-01-02 11:02:00.955

Thesis (MScAgric)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Made available in DSpace on 2016-06-02T19:58:06Z (GMT). No. of bitstreams: 1 6113.pdf: 14480974 bytes, checksum: cca2a2f995c38bc760cbc592a2cee898 (MD5) Previous issue date: 2014-06-06 / Financiadora de Estudos e Projetos / This study analyzes the microclimate effects caused by a water body in São José do Rio Preto city, which is located at an Altitute Tropical Climate region in the São Paulo State, Brazil. The main hypothesis stems from the conjunction among the air masses action in the region combined with the evaporative cooling by the water body in the built environment. The study methodology is based on the physical characterization of different environments that make up the urban environment, in determining procedures of gathering data field, in the analysis of macro and meso climatic characteristics of the region, in the treatment of microclimate data by mapping information and the formulation of guide lines for urban space occupation. The monitoring field data campaigns used meteorological measurements at fixed points to record the behavior of temperature, humidity, solar radiation, evapotranspiration, the wind speed and direction in the urban area, both in the rural environment, in the bank of the dam, in the inner city and in the suburbs. Climate general information of the region were collected by Automatic Weather Station of CIIAGRO Center for Integrated Agricultural Weather Information and the CETESB Station Environmental Company of São Paulo State - which were crossed with the data and the satellite images of INPE-CPTEC Prediction Center of Weather and Climate Research. After the field campaigns, climatic data and physical characteristics of the urban environment were processed using geostatistical methods for mapping the microclimate behavior of the studied urban areas. We concluded that the wind action over the water mass may influence the immediate surroundings, reaching approximately 1.000m depending of the topographical characteristics, of the urban occupation and the atmospheric conditions. Humidification of urban air through the water body can reduce the daily temperature peaks at approximately 3°C, however, the significant difference found in the rates of temperature and humidity in the urban canopy layer clarifies that the 9 km² of the water surface are insufficient to influence the farthest outlying areas of the dam under any climatic conditions. The low penetration of humidified air masses suggests that urban space should favor the passive action of evaporative cooling to cause microclimatic effects to mitigate the temperature amplitude in low vegetated areas and in a highly waterproofed city. / Este estudo analisa os efeitos microclimáticos provocados por corpo d´água sobre a cidade de São José do Rio Preto, localizada em uma região de clima Tropical de Altitude no Estado de São Paulo. A principal hipótese decorre da conjunção entre a atuação das massas de ar da região, com o resfriamento evaporativo provocado pelo corpo d água e com o ambiente construído. A metodologia do estudo se baseia na caracterização física dos diversos ambientes que compõem o espaço urbano, na determinação dos procedimentos de coleta de dados de campo, na análise das características macro e meso climáticas da região, no tratamento de dados microclimáticos através do mapeamento de informações e na formulação de diretrizes para a ocupação do espaço urbano. As campanhas de coleta de dados micrometeorológicos utilizaram medições em pontos fixos para registrar o comportamento da temperatura, da umidade, da irradiância global horizontal, da evaporação, da direção e da velocidade do vento na malha urbana, tanto na área rural como nas margens da represa, no centro urbano e nos bairros periféricos. Os dados climáticos da região foram coletados pela Estação Meteorológica automática do CIIAGRO - Centro Integrado de Informações Agro Meteorológicas e pela estação da CETESB Companhia Ambiental do Estado de São Paulo as quais foram cruzadas com os dados e Imagens de Satélite do Centro de Previsão de Tempo e Estudos Climáticos CPTEC INPE. Após as coletas de campo, os dados climáticos e as informações das características físicas do ambiente urbano foram processados através de métodos geoestatísticos para mapear o comportamento microclimático das áreas urbanas estudadas. Conclui-se que a ação do vento sobre a massa d água pode influenciar no entorno imediato, chegando a influenciar até aproximadamente 1.000m de raio de distância, dependendo das características topográficas, de ocupação e das condições atmosféricas. A umidificação do ar urbano através do corpo d água pode reduzir os picos diários de temperatura em aproximadamente 3°C, no entanto, a expressiva diferença detectada nos índices de temperatura e umidade nas camadas intraurbanas esclarece que os 9 km² da represa municipal são insuficientes para influenciar as zonas periféricas mais distantes dela, sob quaisquer condições climáticas. A pouca penetração das massas umidificadas de ar sugere que o espaço urbano deve favorecer a ação passiva do resfriamento evaporativo para provocar efeitos microclimáticos que amenizem a amplitude térmica nos espaços pouco vegetados e muito impermeabilizados da cidade.

Master of Science / Animal Sciences and Industry / Micheal J. Brouk / Study 1 was performed to assess the effect of an evaporative cooling system (ECS) on core body temperature (CBT) and lying times in lactating dairy cows. Respiration rates and rear udder temperatures (T[subscript u]) were also measured. Trial 1 contained 3 environmental treatments while trial 2 contained 2 environmental treatments. Treatments were: OFF (Cyclone fans and fog shut off), FAN (Cyclone fans only, no fog), and FANFOG (Cyclone fans and fog on) and cows exposed to these 3 environments were housed in a bedded pack barn (PACK) equipped with an ECS or a tie-stall barn (TIE). TIE and PACK cows moved between barns every 8 h for milking and both groups moved opposite of each other. Ambient, barn temperature and relative humidity (RH) measurements in addition to vaginal temperatures and lying times were recorded by sensors which took measurements at 1 min intervals. Respiration rates (BPM), for PACK cows during FANFOG were reduced (P < 0.05) when compared to TIE (53 ± 2.0 vs 64 ± 2.0, respectively) in trial 1. Similar results were found in trial 2. Rear udder temperature was measured and found to be decreased (P < 0.05) in PACK cows while housed under FANFOG vs TIE in trial 1. These results could not be repeated in trial 2 because of greater ambient temperatures. Core body temperature (CBT) was reduced during each trial as shown by less time spent above 39.0°C during FANFOG. During trial 2, PACK spent 5.7 and 8.5 h/d less over a CBT of 39.0°C compared to TIE cows. Total daily lying time was tracked and found to increase for cows exposed to the ECS during PACK but no difference between PACK and TIE. In study 2, the same ECS was used but its effects on nonlactating dairy cows were studied. There was a treatment by h interaction for vaginal temperature showing the greatest effects during the afternoon h where FANFOG had numerically decreased CBT vs FAN. FANFOG cows spent reduced time over a CBT of 39.0°C and greater time < 38.0°C. FANFOG cows also had increased lying times of 1.7 h/d compared to FAN.

Submitted by Maike Costa (maiksebas@gmail.com) on 2017-05-30T13:23:04Z No. of bitstreams: 1 arquivototal.pdf: 4122631 bytes, checksum: 3dbd65166aa3a3cad90e903290833e6a (MD5) / Made available in DSpace on 2017-05-30T13:23:04Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4122631 bytes, checksum: 3dbd65166aa3a3cad90e903290833e6a (MD5) Previous issue date: 2016-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The consumption of electricity in our social environment such as in houses, apartments, business, industries, hospitals, it’s achieved thanks to an equipment that makes the levels of tension and electric current acceptable as demanded by the standards, so we can benefit from electricity in a safe and efficient way, these equipment are the power transformers. Due your relevance, techniques that retard or avoid the failures in these equipment, aiming a better availability and a smaller number of maintenance stops, are the theme of several researchers and studies centers. A very common failure in medium and large transformers that are used in transmission and distribution of power, is the degradation of the insulating function of transformer's core that it is caused mainly by the adverse gradient of temperature that circulates in the core through the insulating oil. The present work analyzes the efficiency of a transformer's cooling auxiliary system, that aims dissipate the heat absorbed by the oil in a quick and efficient way, decreasing the degradation of the insulating function and increasing its lifespan. The system consist of water spray nozzles, that it will be installed in the transformer’s radiator, in front of the fans, in the same direction of the air flow. The water spraying in the air flow, will cause a temperature decrease and a humidity increase, due to a phenomenon known as evaporative cooling, where heat from the air makes the small drops of water evaporate quickly. It will be analyzed the water flow rate in the spraying, the amount and placement of the water spray nozzles through the radiator and the air flow of the fans. So the system has thermal and energetic efficiency. Will be used a control system that includes a variable-frequency drive (VFD), temperature sensors and a data acquisition board (DAQ), all monitored through LabVIEW. / O consumo de energia elétrica no nosso convívio social como, casas, apartamentos, comércio, indústria, hospitais, é conseguido graças a um equipamento que torna os níveis de tensão e corrente elétrica em valores aceitáveis exigidos por norma, para que possamos usufruir da energia elétrica de maneira segura e eficiente, esses equipamentos são os transformadores de força ou de potência. Visto sua importância, técnicas que retardam ou evitem falhas nesse equipamento, visando a maior disponibilidade e com isso menos paradas para manutenção, são tema de estudo de diversos pesquisadores e centros de ensino. Uma falha bastante comum em transformadores de médio a grande porte que são utilizados na transmissão e distribuição de energia, é a degradação do papel isolante do núcleo do transformador, que é causada principalmente pelo gradiente adverso de temperatura que circula no núcleo através do óleo isolante. Logo o presente trabalho analisa a eficiência de um sistema auxiliar de arrefecimento do transformador, que visa dissipar o calor absorvido pelo óleo de maneira rápida e eficiente, diminuindo a degradação do papel isolante e aumentando sua vida útil. O sistema será composto por bicos pulverizadores de água, que serão instalados nos radiadores do transformador, em frente aos ventiladores, no mesmo sentido do fluxo de ar. A pulverização de água nesse fluxo de ar, irá causar uma diminuição da temperatura e um aumento de umidade, isso devido a um fenômeno conhecido como resfriamento evaporativo, onde as pequenas gotas de água recebem o calor do ar e se evaporam rapidamente. Será analisado a vazão de água na pulverização, a quantidade e o posicionamento dos bicos ao longo do radiador e o fluxo de ar dos ventiladores, para que o sistema tenha eficiência térmica e energética. Será utilizado um sistema de controle composto por inversores de frequência, sensores de temperatura e placa de aquisição de dados, que serão monitorados pelo LabView.

Made available in DSpace on 2015-05-08T15:00:06Z (GMT). No. of bitstreams: 1 parte1.pdf: 1140814 bytes, checksum: 542f51d418daba0191fb72d0eefa3504 (MD5) Previous issue date: 2010-11-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work is presented in an air conditioning system using evaporative cooling coupled with desiccant rotor, which presents itself as an alternative to refrigeration system for vapor compression. In this sense, was mounted on the Solar Energy Laboratory UFPB in Joao Pessoa, an industrial-scale prototype of a desiccant cooling system for air conditioning, using two rotors desiccants, two rotary heat exchangers, evaporative coolers three, two burners natural gas, a water pump high pressure and five centrifugal fans. The proposal is to analyze the behavior of the system on the climatic conditions of hot and humid climate and also compare the results with other experimental and numerical. The system can operate in three configurations for operation and you were obtained and recorded data as the prototype cooling capacity, COP and system psychrometric conditions of the air supplied equipment to the air conditioned environment. All work done in assembling the prototype and the field of technology applied to air conditioning with desiccant rotor under the conditions of hot and humid climate are presented and analyzed. The results show that, even when operating in adverse weather conditions, the system can achieve performance similar to the vast majority of cooling systems using desiccant rotor and the thermal comfort can be achieved under conditions of climate in the summer of Joao Pessoa. / Neste trabalho é apresentado um sistema de condicionamento de ar utilizando resfriamento evaporativo acoplado a rotores dessecante, que se apresenta como uma alternativa ao sistema de refrigeração por compressão de vapor. Neste sentido, foi montado no Laboratório de Energia Solar da UFPB em João Pessoa, um protótipo em escala industrial de um sistema de refrigeração dessecante para condicionamento de ar, utilizando dois rotores dessecantes, dois trocadores de calor rotativos, três resfriadores evaporativos, dois queimadores a gás natural, uma bomba d água de alta pressão e cinco ventiladores centrífugos. A proposta é analisar o comportamento do sistema sobre as condições climáticas do clima quente e úmido e também comparar os resultados com os de outros trabalhos experimentais e numéricos. O sistema pode operar em três configurações de funcionamento e para estás foram obtidos e registrados dados como: Potência frigorífica do protótipo, COP do sistema e condições psicrométricas do ar fornecido pelo equipamento ao ambiente climatizado. Todo o trabalho desenvolvido na montagem do protótipo e domínio da tecnologia aplicada para o condicionamento de ar com rotores dessecantes, nas condições do clima quente e úmido são apresentadas e analisadas. Os resultados obtidos demonstram que, mesmo operando em condições climáticas adversas, o sistema pode atingir desempenho semelhante ao da grande maioria dos sistemas de condicionamento de ar usando rotores dessecantes e que as condições de conforto térmico podem ser alcançadas nas condições do clima de João Pessoa no verão.