Improvements in Air Intake on Frame 6 Gas Turbines

Työssä tarkastellaan kahta kaasuturbiinin imuilman sisäänottojärjestelmän kehitysmenetelmää, imuilman jäähdytystä ja sähköstaattista suodatusta. Imuilman jäähdytysmenetelmien tarkastelussa käytettiin kahta kaasuturbiinin tehonlisäystekniikoiden laskentatyökalua. Arviointi kohdistettiin Glanford Brigg Generating Station -voimalaitoksen kaasuturbiinityyppiin ja paikallisiin englantilaisiin ilmasto-olosuhteisiin. Tarkastelussa olivat kostutusjäähdytys ja overspray. Tuloksia vertailtiin keskenään ja näiden perusteella arvioitiin menetelmien vaikutuksia tehoon, hyötysuhteeseen sekä veden kulutukseen. Sähköstaattisen suodattimen prototyyppi oli rakennettu Briggin voimalaitokselle. Järjestelmää kehitetään kaupalliseksi tuotteeksi ja tätä varten kerättiin tekninen dokumentaatio kokonaisuudeksi, jota voitiin hyödyntää tuotteistusprosessissa. Imuilman jäähdyttämisellä voidaan saavuttaa merkittävä tehonlisäys ilmasto-olosuhteista riippuen. Menetelmällä voidaan myös tasata lämpötilan vuorokausi-vaihtelusta aiheutuvia tehoeroja. Sähköstaattisen suodattimen prototyyppi saavutti kehitysvaiheelle asetetut tavoitteet. Sähköstaattinen suodatus tarjoaa useita etuja perinteiseen mekaaniseen suodatukseen verrattuna.

Effect of process variables on fluiddynamics and adhesion efficiency during spouted bed coating of hard gelatine capsules

This article presents an evaluation of the effects of the spouted bed design and operating conditions on system fluiddynamics and process performance during enteric coating of hard gelatine capsules. The design parameters studied were the column diameter (150 mm and 200 mm), the included angle of the conical base, gamma (60 degrees or 40 degrees) and the presence or absence of a Venturi inserted before the inlet air orifice. The process variables studied were the ratio between the feed flow rate of the coating suspension to the spouting gas flow rate (W(s)/W(g)), the mass of capsules loaded to the equipment (M(0)), and the ratio between the Spouting gas flow rate to the gas flow rate at minimum spouting condition (Q/Q(ms)). The response variables were the rate of increase of the capsules mass (K(1)), and the adhesion efficiency (eta). The linear regression equation for the dependent variable K, in terms of the independent variables adequately described the process with an r(2) value of 0.872. Analysis of variance (ANOVA) revealed that increasing of W(s)/W(g), Q/Q(ms) and gamma significantly increased the adhesion efficiency. Adhesion efficiencies higher than 90% were achieved by selecting precise coating conditions, indicating the feasibility of the process for coating of hard gelatine capsules. (C) 2008 Elsevier B.V. All rights reserved.

Evaluation of various pre-treatments for the dehydration of banana and selection of suitable drying models

The thin-layer drying behaviour of bananas in a beat pump dehumidifier dryer was examined. Four pre-treatments (blanching, chilling, freezing and combined blanching and freezing) were applied to the bananas, which were dried at 50 degreesC with an air velocity of 3.1 m s(-1) and with the relative humidity of the inlet air of 10-35%. Three drying models, the simple model, the two-term exponential model and the Page model were examined. All models were evaluated using three statistical measures, correlation coefficient, root means square error, and mean absolute percent error. Moisture diffusivity was calculated based on the diffusion equation for an infinite cylindrical shape using the slope method. The rate of drying was higher for the pre-treatments involving freezing. The sample which was blanched only did not show any improvement in drying rate. In fact, a longer drying time resulted due to water absorption during blanching. There was no change in the rate for the chilled sample compared with the control. While all models closely fitted the drying data, the simple model showed greatest deviation from the experimental results. The two-term exponential model was found to be the best model for describing the drying curves of bananas because its parameters represent better the physical characteristics of the drying process. Moisture diffusivities of bananas were in the range 4.3-13.2 x 10(-10) m(2)s(-1). (C) 2002 Published by Elsevier Science Ltd.

Characterization and drying of caja bagasse (Spondias mombin L.) in a tray dryer using a factorial planning

The caja (Spondias mombin L.) is used in the manufacture of ice-cream, jams, pulps, beverages being also consumed in natura. One of the most important procedures in food conservation is drying, considering that most fresh fruits contain approximately 80% of water. Food drying is used to obtain two basic aspects: (1) the economic factor; in the shipping and handling of the product; (2) at the manipulation; once dried and grinded, the material is rehydrated, at desirable levels, to formulate a new product as in ice cream, jams, yoghurts and drinks and may also be added to pasta, biscuits and other industrialized products. The aim of this study was to investigate the kinetics of caja bagasse drying in a fixed-bed tray dryer, using central composite factorial planning. The following factors were evaluated: temperature (55, 65 and 75 ºC), dryer inlet air velocity (3.2, 4.6 and 6.0 m.s-1) and cake thickness (0.8, 1.2 and 1.6 cm) where the response of the considered variable was caja bagasse moisture content (b.s.) and the results showed that the main effects and their interactions were significant at a 95% confidence level being the best condition obtained at temperature of 75 ºC, velocity of 6.0 m.s-1 and cake thickness of 0.8 cm.

Microencapsulation of pequi pulp by spray drying: use of modified starches as encapsulating agent

The aim of this study was to evaluate the microencapsulation of pequi pulp by spray drying. A central composite rotational design was used in order to evaluate the effect of the independent variables: inlet air temperature, surfactant concentration and modified starch concentration. The dependent variables were assumed as yield of the process and the product features microencapsulated. A selection of the best process condition was performed to obtain the best condition of a product with the highest vitamin C and carotenoids content. Powders showed moisture content below 2%. The experimental values of hygroscopicity, yield, water activity, total carotenoids and vitamin C powders ranged from 7.96 to 10.67 g of adsorbed water/100g of solids, 24.34 to 49.80%, 0.13 to 0.30, 145.78 to 292.11 mg of ascorbic acid/g of pequi solids and 15.51 to 123.42 mg of carotenoids/g of pequi solids, respectively. The inlet air temperature 140°C, the surfactant concentration of 2.5% and the modified starch concentration of 22.5% was recommended as the selected condition. By the scanning electron microscopy, it was observed that most of the particles had spherical shape and smooth surface.

Influence of spray drying conditions on the physical properties of dried pulp tomato

A complet factorial experimental design was applied to determinate the influence of the variable inlet air temperature, feed flow rate, and atomizer speed on the physical properties of the tomato pulp powder. Results showed that these variables had a significant positive effect on the moisture content, apparent density, and particle size and no significant effects on the porosity and true density. The best spray drying conditions to produce lower moisture content and higher apparent density tomato powder were inlet air temperature of 200 °C, feed flow rate of 276 g/min, and atomizer speed of 30000 rpm.

Microencapsulation of babassu coconut milk

The objective of this study was to obtain babassu coconut milk powder microencapsulated by spray drying process using gum Arabic as wall material. Coconut milk was extracted by babassu peeling, grinding (with two parts of water), and vacuum filtration. The milk was pasteurized at 85 ºC for 15 minutes and homogenized to break up the fat globules, rendering the milk a uniform consistency. A central composite rotatable design with a range of independent variables was used: inlet air temperature in the dryer (170-220 ºC) and gum Arabic concentration (10-20%, w/w) on the responses: moisture content (0.52-2.39%), hygroscopicity (6.98-9.86 g adsorbed water/100g solids), water activity (0.14-0.58), lipid oxidation (0.012-0.064 meq peroxide/kg oil), and process yield (20.33-30.19%). All variables influenced significantly the responses evaluated. Microencapsulation was optimized for maximum process yield and minimal lipid oxidation. The coconut milk powder obtained at optimum conditions was characterized in terms of morphology, particle size distribution, bulk and absolute density, porosity, and wettability.

Influence of spray drying operating conditions on microencapsulated rosemary essential oil properties

Spray drying is an important method used by the food industry in the production of microencapsulated flavors to improve handling and dispersion properties. The objective of this study was to evaluate the influence of the process conditions on the properties of rosemary essential oil microencapsulated by spray drying using gum Arabic as encapsulant. The effects of the wall material concentration (10-30%), inlet air temperature (135-195 ºC), and feed flow rate (0.5-1.0 L.h-1) on the moisture content, hygroscopicity, wettability, solubility, bulk and tapped densities, particle density, flowability, and cohesiveness were evaluated using a 2³ central composite rotational experimental design. Moisture content, hygroscopicity and wettability were significantly affected by the three factors analyzed. Bulk density was positively influenced by the wall material concentration and negatively by the inlet air temperature. Particle density was influenced by the wall material concentration and the inlet air temperature variables, both in a negative manner. As for the solubility, tapped density, flowability, and cohesiveness, the models did not fit the data well. The results indicated that moderate wall material concentration (24%), low inlet air temperature (135 ºC), and moderate feed flow rate (0.7 L.h-1) are the best spray drying conditions.

Sähkösuodattimen mahdollisuudet sisäilman parantajana

Diplomityön tavoitteena oli selvittää, kuinka sähkösuodattimella voidaan vaikuttaa sisäilman laatuun ja kuinka kilpailukykyinen vaihtoehto pienkiinteistöissä sähkösuodatin on perinteisiin kuitusuodattimiin verrattuna. Teoriaosassa tarkasteltiin, kuinka ilman hengitettävät hiukkaset muodostuvat ja miten ne vaikuttavat sisäilman laatuun sekä ihmisten terveyteen. Tarkasteltiin hiukkasten koon, lukumäärän, massan ja pinta-alan yhteyksiä niiden terveysvaikutuksiin. Ultrapienet hiukkaset ovat terveydelle haitallisimpia, koska hiukkasten lukumäärä ja pinta-ala lisäävät terveyshaittoja enemmän kuin hiukkasten massa. Tutkittiin pienkiinteistöjen ilmanvaihtoratkaisuja ja erilaisia tuloilmanpuhdistus-menetelmiä. Soveltavassa osassa tarkasteltiin sähkösuodattimen toimintaa ja sen mahdollisuuksia sisäilman parantajana verrattuna perinteisiin kuitusuodattimiin. Tehtiin sähkösuodattimen ja kuitusuodattimen välinen elinkaarikustannusvertailu keskisuurelle omakotitalolle. Kirjallisuuden ja tutkimushavaintojen perusteella sähkösuodattimen suurin etu muihin suodattimiin verrattuna on sen kyky poistaa kaiken kokoisia, myös ultrapieniä, hengitettäviä hiukkasia ja siten tehokkaasti vähentää hengitettävien hiukkasten lukumäärää ja pinta-alaa. Tällä voi olla vaikutusta yleisten terveyshaittojen ja ympäristöherkkyyden ennaltaehkäisemisessä. Ympäristöherkkyyteen sairastuneiden oireiluun sähkösuodatin voi tuottaa helpotusta kotioloissa ja siirrettävän ilmanpuhdistimen avulla myös työpaikoilla. Elinkaarikustannusvertailun perusteella selvisi, että sähkösuodatin on kalliimmasta hinnastaan huolimatta kokonaiskustannuksiltaan selvästi edullisempi vaihtoehto kuin kuitusuodattimet. Sähkösuodattimen haasteena on uuden teknologian lanseeraaminen pientalorakentamiseen. Pienrakennusten tuloilman puhdistusmenetelmien kehittämisellä olisi mahdollista parantaa suomalaisten elämänlaatua ja saavuttaa merkittäviä säästöjä terveydenhoitokuluissa.

Numerical study of a M-cycle cross-flow heat exchanger for indirect evaporative cooling

In this paper, numerical analyses of the thermal performance of an indirect evaporative air cooler incorporating a M-cycle cross-flow heat exchanger has been carried out. The numerical model was established from solving the coupled governing equations for heat and mass transfer between the product and working air, using the finite-element method. The model was developed using the EES (Engineering Equation Solver) environment and validated by published experimental data. Correlation between the cooling (wet-bulb) effectiveness, system COP and a number of air flow/exchanger parameters was developed. It is found that lower channel air velocity, lower inlet air relative humidity, and higher working-to-product air ratio yielded higher cooling effectiveness. The recommended average air velocities in dry and wet channels should not be greater than 1.77 m/s and 0.7 m/s, respectively. The optimum flow ratio of working-to-product air for this cooler is 50%. The channel geometric sizes, i.e. channel length and height, also impose significant impact to system performance. Longer channel length and smaller channel height contribute to increase of the system cooling effectiveness but lead to reduced system COP. The recommend channel height is 4 mm and the dimensionless channel length, i.e., ratio of the channel length to height, should be in the range 100 to 300. Numerical study results indicated that this new type of M-cycle heat and mass exchanger can achieve 16.7% higher cooling effectiveness compared with the conventional cross-flow heat and mass exchanger for the indirect evaporative cooler. The model of this kind is new and not yet reported in literatures. The results of the study help with design and performance analyses of such a new type of indirect evaporative air cooler, and in further, help increasing market rating of the technology within building air conditioning sector, which is currently dominated by the conventional compression refrigeration technology.

Secagem de grãos de girassol em leito fixo e em leito de jorro

This work studies two methods for drying sunflower grains grown in the western region of Rio Grande do Norte, in the premises of the Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte - IFRN - Campus Apodi. This initiative was made because of the harvested grain during the harvest, being stored in sheds without any control of temperature, humidity etc. Therewith, many physical, chemical and physiological characteristics are compromised and grains lose much quality for oil production as their germination power. Taking into account that most of the stored grain is used for replanting, the studied methods include drying of grains in a thin layer using an oven with air circulation (fixed bed) and drying in a spouted bed. It was studied the drying of grains in natura, i.e., newly harvested. The fixed bed drying was carried out at temperatures of 40, 50, 60 and 70°C. Experiments in spouted bed were performed based on an experimental design, 2² + 3, with three replications at the central point, where the independent variables were grains load (1500, 2000 and 2500 g) and the temperature of the inlet air (70, 80, and 90 °C), obtaining the drying and desorption equilibrium isotherms. Previously, the characteristic curves of the bed were obtained. Both in the fixed bed as in the spouted bed, drying and desorption curves were obtained by weighing the grains throughout the experiments and measurements of water activity, respectively. The grains drying in the spouted bed showed good results with significant reduction of processing time. The models of FICK and PAGE were fitted to the experimental data, models which will represent the drying of grains both in the fixed bed as in the spouted bed. The desorption curves showed no influence of the processing temperature in the hygroscopic characteristics of the grains. The models of GAB, OSWIN and LUIKOV could well represent the desorption isotherms

Ecological impacts from syngas burning in internal combustion engine: Technical and economic aspects

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Transferência de calor em leitos fixos com aplicação em reatores de fermentação em estado sólido

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Secagem por atomização do suco de uva: microencapsulação das antocianinas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modelagem e simulação de ciclos a gás com resfriamento de ar na entrada

The optimization of energy generation systems has become a key issue for technological and social development, mainly in developing countries, where the electricity consumption rises sharply. Gas turbine cycle is an electricity generating system, which studies have demonstrated that inlet air cooling increases net power and thermal efficiency. Thus, this study intends to quantify these parameters for environments with different ambient temperature and relative humidity. Two types of air cooling were used: evaporative and absorption systems. The configuration parameters only with the gas turbine cycle were compared to those whose configuration allowed cooling. First, it was analyzed only evaporative cooling. Next, the absorption system was used for analysis. The last configuration mixed these two methods, dividing equally its flow. The results showed that thermal efficiency and net power increase in any case of cooling, with absorption system more advantageous in terms of generated energy, where an increase between 1 and 2 MW was observed, depending on the ambient conditions . When the two methods were working together at low relative humidity, it showed a thermal efficiency increase compared to absorption system, up to 2.4%. Evaporative cooling was less effective, but it is a good and cheap possibility to increase the cycle parameters at high temperature and low relative humidity