An indirectly heated solar drier fitted with a flat plate collector and a directly heated solar drier were compared with open air sun drying of cocoa beans under field conditions in St. Lucia. Sun drying was conducted on two surfaces, perforated steel and non perforated wood. The methods were examined for the ability to adequately dry fermented beans and effect on quality. Loading rates of 13.5, 26.9 and 40.4 kg/m$ sp2$ were examined. / Temperature increases of 15$ sp circ$C and 20$ sp circ$C above ambient were achieved in the indirect and direct drier, respectively. The solar driers were more efficient than sun drying units at removing moisture throughout at loading rates of 26.9 and 40.4 kg/m$ sp2$ but only in the initial stages at 13.5 kg. External mould development was therefore reduced. Open air sun drying on the wooden surface proved more effective in the final stages at 13.5 kg/m$ sp2$. / The dried beans were of similar internal quality despite faster drying in the driers. The various drying methods and loading rates produced beans of similar pH while only loading rates affected titratable acidity differently. The direct solar drier achieved lower final moisture levels at high loads and was the cheaper alternative.

The Republic of Guinea is located on the west coast of Africa at about 11° North latitude. A large portion of Guinea's supply of protein is dried fish. The actual drying method operates under open air, the foodstuff being unprotected from unexpected rains, windborne dirt and dust, and from infestation by insects, rodents, and other animals. More, the deforestation rate is increasing year after year, depleting the source of fuel for drying. Practical ways of drying fish cheaply and sanitarily would be welcome.The present work develops a prototype solar dryer on the basis of natural convection of air. The device is comprised of a glazed flat plate collector, a furnace with translucent walls, and an air tunnel adjoining the two. Air entering the collector is heated and flows into the furnace where energy is absorbed by pieces of fish placed on horizontal racks. The air exits through an opening in the top of the device carrying moisture with it.Using the prototype solar dryer, a fish drying experiment was conducted at the Center for Energy Research, Education, and Service (CERES) at Ball State University. The primary objectives were to investigate drying rates, times, and loads expected for a dryer constructed using simple techniques and materials readily available in the Republic of Guinea. The drying experimental results are in many ways similar to those reported by previous authors.The solar dried product appears to be superior to the product of current drying methods and the foodstuff is protected from infestation or contamination during drying.Future work suggested by the project experience includes refinement of the dryer design and additional fish drying experimentation. An economic analysis would also yield information on the feasibility of widespread use of solar dryers for drying of fish in the Republic of Guinea. / Department of Physics and Astronomy

No description available.

The purpose of this study was to determine an answer to the question: What are the effects of washer rinse temperature, final washer spin time, or dryer setting on the energy consumption of a household electric clothes dryer? The data were collected in July and August, 1981, using a Maytag washer and dryer. The preconditioned load used was a variation of the Association of Home Appliance Manufacturers' standard eight pound load with fiber content of cotton and polyester. Eight combinations of the independent variables, rinse temperature, spin time, and dryer setting, were replicated five times. Room temperature, relative humidity, and barometric pressure were monitored. Statistical procedures utilized in data analysis included Pearson product-moment correlation coefficients, means, standard deviations, ranges and analysis of variance. The combination requiring the most energy, 3.403 kwh, was cold rinse, short spin time, and extra dry higher setting, and the combination requiring the least energy, 2.588 kwh, was warm rinse, long spin time, and normal dryer setting. However, it was calculated that it required 2.3 kwh to heat the warm water used in rinsing. Therefore, it is recommended that consumers can save the most energy using a combination of cold rinse, long spin time, and normal dryer setting. / Master of Science

<p style="text-align: justify">Doktorska disertacija &quot;Modelovanje mehanizma prenosa toplote pri konvektivnom su&scaron;enju i utvrđivanje numeričkih pokazatelja&quot; - sadrž i eksperimentalna i teorijska istraživanja vezana za metodu konvektivnog su&scaron;enja. Izvr&scaron;ena su istraživanja parametara sistema konvektivne pneumatske su&scaron;are u eksploatacionim uslovima proizvodnje. Na osnovu rezultata ispitivanja utvrđeni su: modeli kinetike su&scaron;enja, energetski bilansi, koeficijenti prenosa toplote, optimalni režim su&scaron;enja, modeli mehanizma prenosa toplote, numerički pokazatelji i izvr&scaron;ena njihova analiza.</p> / <p>PhD Thesis &quot;Modelling the mechanism for heat<br />transfer at the convective drying and establishing of<br />numerical readers&quot; - contains the experimental and<br />theoretical researches connected with the convective<br />drying method. The parameter researches of the<br />convective pneumatic dryer system in the<br />exploitation conditions in production, are done. On<br />the basis of the testing results are established: the<br />models of drying kinetics, energetic bilances, heat<br />transfer coefficients, optimal regime of drying, heat<br />transfer models mechanism, numerical readers and<br />there was also realized their analysis.</p>

Compressed air is widely used particularly in industry. In order to increase the quality of the process and lifetime of the machine, the compressed air should be dried. Therefore the air is used after compression and drying processes. The most commonly used machines that do this process are called &ldquo / Refrigerant Air Dryers&rdquo / . These air dryers are designed to cool and dehumidify the moist air. The process of decreasing temperature is carried out by a refrigerant, R134a. Unlike design conditions, dryers are working in variable loads (variable compressed air flow rates). An experimental setup is prepared for analyzing the variance on the machine and the performance under these variable loads. This thesis includes the design, preparation and the modification of the refrigeration experimental setup for refrigerant air dryers. The setup is tested under three different conditions and the results are compared.

Textile dyeing and finishing industry uses dryers/tenters for drying and heat-setting fabrics. A very large fraction of the heating value of the fuel consumed in the burner ends up as waste in the dryer exhaust. An initial calculation showed that up to 90% of the energy consumed in the tenter is wasted. Therefore, quantifying the energy waste and determining drying characteristics are vitally important to optimizing the tenter and dryer operations. This research developed a portable off-line gas chromatography-based characterization system to assess the excess energy consumption. For low-demanding heat-setting situations, energy savings can be realized quickly. On the other hand, there are demanding situations where fabric drying represents the production bottleneck. The drying rate may be governed either by the rate of heat transport or by the rate of moisture transport. A mathematical model is being developed that incorporates both these processes. The model parameters are being obtained from bench-scale dryer studies in the laboratories. The model will be validated using production scale data. This will enable one to predict optimization dryer operation strategies.

Hungary’s share of renewable energy in 2010 was 7.9 %, and their renewable energy goal for 2020 is 14.65 %. Geothermal energy is one option that could help to achieve the goal, since Hungary has favorable bedrock, the temperature gradient is above average and thepermeability is high. Today Hungary is importing just over half of its primary energy supply. Because of political conflicts between nations Hungary wants to expand its own production of energy. One of the major investments implemented was to build the largest geothermal heating plant in central Europe, located in Miskolc. This degree theses aims is to raise the capacity factor for this heating plant. To achieve this objective, a survey of how grain dryers and absorption chillers could increase the heat load in the summer has been performed. With grain dryers that only dries wheat, the capacity factor for the geothermal heating plant in Miskolc increased by 2.6 % and by 4.4 % for the absorption chiller. Although surveys have been carried out for a specific case the idea can be implemented in other heating plants. Keywords: Capacity factor, geothermal energy, wheat dryers and absorptions chiller.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-03T20:13:43Z No. of bitstreams: 1 FABIANA PIMENTEL MACÊDO FARIAS - TESE PPGEP 2006..pdf: 6819431 bytes, checksum: 61825d33b2b61b2732d80e7e82b96b05 (MD5) / Made available in DSpace on 2018-09-03T20:13:43Z (GMT). No. of bitstreams: 1 FABIANA PIMENTEL MACÊDO FARIAS - TESE PPGEP 2006..pdf: 6819431 bytes, checksum: 61825d33b2b61b2732d80e7e82b96b05 (MD5) Previous issue date: 2006-04-19 / Os ciclones são equipamentos utilizados em processos químicos, em diversas operações unitárias, com o objetivo de promover a separação de sólido e/ou líquido de uma corrente gasosa e secar sólidos. Neste sentido, o presente trabalho propõe um estudo teórico da termofluidodinâmica de um ciclone como secador. O modelo matemático considera escoamento tri-dimensional, turbulento e estacionário para a fase gasosa, e o modelo Lagrangeano para as partículas. As equações diferenciais que representam o fenômeno físico foram resolvidas numericamente pelo método dos volumes finitos, com esquema de interpolação UPWIND para os termos convectivos e o algoritmo SIMPLEC para o acoplamento pressão-velocidade. Como aplicação, a metodologia foi usada para predizer a secagem do bagaço de cana-de-açúcar em um ciclone. As simulações foram realizadas utilizando o código computacional CFX-3D. Resultados do teor de umidade, temperatura e variações dimensionais da partícula, distribuição de velocidade, pressão e temperatura do ar de secagem, para diversas condições do ar, geometria do ciclone e velocidade inicial da partícula são apresentados e analisados. Constatou-se o caráter tridimensional do escoamento gás-partícula no interior do ciclone com presenças de regiões de zonas de recirculação e de inversão de fluxo, apresentando razoável concordância com os dados experimentais. Verificou-se que a cinética de secagem, o aquecimento e o tempo de residência das partículas são afetadas pelas condições do ar de secagem e geometria do ciclone, e quando comparadas com dados experimentais apresentaram boa aproximação. O ciclone com seção de entrada quadrada se mostrou mais eficiente, do ponto de vista de secagem, quando comparados com os dutos de seção retangulares vertical e horizontal. / Cyclones are equipments very used in chemical processes, in several units operations. Their aim is to promote the solid and/or a liquid separation from a gas stream and dry solids. In this sense, the present work proposes a theoretical study of thermal fluid dynamics of a cyclone as dryer. The mathematical model considers three-dimensional, turbulent and stationary flow for gas phase, and Lagrange model for particles. The governing equations were solved numerically with the finite-volumes method, using UPWIND interpolation scheme for convective terms and algorithm SIMPLEC for pressure-velocity coupling. As an application, the methodology was used to predict the sugar cane bagasse drying in a cyclone. Simulations had been carried out using the computational code CFX-3D. Results of the moisture content, temperature and dimensional variations of the particles and velocity, pressure and temperature distributions of the air drying, to several air conditions, shape of the cyclone and initial velocity of particle is presented and analyzed. Three-dimensional gas-particle flow, recirculation zones and inversion flow were verified inside the cyclone. Numerical data fitted well experimental ones. It was verified that the kinetic drying, temperature and residence time of the particles were affected by air drying conditions and cyclone geometry. Cyclone with square inlet section were more efficient to dry than cyclone with vertical and horizontal rectangular section duct.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-10-02T11:11:27Z No. of bitstreams: 1 RENATO FONSECA ARAGÃO - TESE (PPGEP) 2007.pdf: 2987453 bytes, checksum: c87484ad75e7b482ac6c622ba7db5c14 (MD5) / Made available in DSpace on 2018-10-02T11:11:27Z (GMT). No. of bitstreams: 1 RENATO FONSECA ARAGÃO - TESE (PPGEP) 2007.pdf: 2987453 bytes, checksum: c87484ad75e7b482ac6c622ba7db5c14 (MD5) Previous issue date: 2007-12-17 / A secagem de fatias de caju em secadores convencionais de bandejas e em secadores solares é alternativa para atender aos pequenos produtores, que com a utilização desta técnica, possam agregar valor aos seus produtos e minimizar as perdas. No desenvolvimento de secadores é necessário conhecer as propriedades termofísicas do material a secar, as relações de equilíbrio higroscópico bem como dispor de informações acerca da cinética de secagem. De acordo com isto, este trabalho teve como objetivo poder oferecer uma alternativa tecnológica viável de modo a poder otimizar o desempenho do equipamento e a qualidade do produto. Foram determinadas as propriedades térmicas e físicas do pedúnculo do caju em função do teor de umidade. Foi verificado que entre três modelos matemáticos analisados para o equilíbrio higroscópico das fatias de caju o modelo de GAB é o que melhor representa a curva de umidade de equilíbrio. Foi estudada a cinética de secagem, em diferentes condições operacionais com temperaturas variando de 60 a 80 0C, velocidade do ar de secagem na faixa de 1 a 1,8 ms-1 e altura do leito variando de 1 a 3 cm. Para a modelagem matemática foi utilizado o modelo difusional baseado na 2a lei de Fick, que se mostrou adequado para predizer a cinética de secagem do caju. Para analisar o desempenho do secador de bandejas foi estudado a eficiência energética global média, o índice de saturação do ar e o teor de umidade final do produto após 300 minutos de operação. Foi elaborado um planejamento fatorial 23 com três experimentos no ponto central, tendo como variáveis independentes a temperatura, velocidade do ar de secagem e espessura do leito, e como variáveis resposta a eficiência energética global o índice de saturação e o teor de umidade final. Os resultados obtidos para a eficiência energética variaram de 5,12 a 18,86%. Para o índice de saturação do ar a variação foi de 5,35 a 38,38%. As superfícies de respostas geradas mostraram que estes resultados podem ser melhorados com o aumento da carga nas bandejas do secador e a diminuição da velocidade do ar de secagem. Foram implementadas modificações no programa “Secador” desenvolvido em linguagem FORTRAN para simular a secagem de fatias de caju nas bandejas do secador. Foram acrescentadas sub-rotinas para implementar no modelo as variações das propriedades físicas e térmicas do caju em função do teor de umidade, coeficiente de difusão variável, umidade de equilíbrio em função da temperatura e da umidade relativa do ar. Observou-se que com relação a predição da temperatura e umidade do ar o modelo apresenta bons resultados, enquanto que com relação a temperatura e umidade da fruta, é necessário fazer alguns ajustes. Os resultados aqui apresentados mostram a viabilidade do uso de secadores de bandejas e permite o dimensionamento e otimização destes em escala industrial, adequados para atender pequenos produtores na obtenção de fatias de caju secas. / The drying of cashew slices in common tray or solar dryers are alternatives to serve small farmers, who can aggregate value to their product and minimize losses, using this technique. During the development of dryers, it’s necessary to know the thermal-physical properties of the material to be dried, the hygroscopic equilibrium relation, as well as to be aware about drying kinetics. According to that, this work had the objective to offer a viable technological alternative in order to optimize the development of the equipment and product quality. The thermal and physics properties of cashew apple were determined in function of moisture content, regarding the hygroscopic equilibrium, it was verified that, among three mathematic models, the GAB best represents the cashew moisture equilibrium. It was studied the cashew drying kinetic, in different operational conditions, with temperature of 60 to 80ºC, air drying velocity of 1 to 1.8m s-1 and bed height varying between 1 to 3cm. For the mathematic modeling it was used the diffusional model based on Fick’s 2nd law, which is suitable to predict the cashew drying kinetics. In order to analyze the development of tray dryer it was studied the mean global energetic efficiency, the air saturation index, and the final moisture content of the product after operating during 300 minutes. It was prepared a factorial planning 23 with three experiments in central point, involving temperature, air drying velocity and bed thickness as independent variables, and global energetic efficiency, air saturation index, and final content moisture as response variables. The obtained results showed that the energetic efficiency varied from 5.12 to 18.86%, whereas the variation for the air saturation index was from 5.35 to 38.38%. The generated response surface show that these results can be improved by increasing the loading into the dryer trays and by decreasing the drying air velocity. It was implemented some changes in the “Secador” program developed in FORTRAN language to simulate the cashew slices drying in the dryer trays. Sub-routines were added in order to implement, in the model, cashew physics and thermal properties variations as a function of moisture content, variable diffusion coefficient, equilibrium moisture content in function of tools for large scale units, suitable to attend small farmers.