Optimization of an RTS Eco Dryer via Slot Nozzle Simulations
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
In the process of coating plates, a very thin layer of chemicals can be applied to the surface of the plate in order to increase the adhesion of the coating. In order to apply the chemical it is mixed in water and painted on to the plate by using a mechanical roller. However, with water on the plate other undesirable problems may arise, such as corrosion, so after the painting the plate is transported through a dryer where a series of nozzles are designed to direct streams of hot air onto the plate in order to evaporate the water from the surface. A similar process is used in metallization of plates, where a layer of zinc is applied onto the plate. This is done to protect the material from wet storage stain, a white layer of corrosion which may appear when the plate is being stored. In this case the dryer is placed at the end of the production line instead of in the beginning.The RTS eco dryer is a product designed and sold by Relitor in Gammelstad, its sole purpose is to evaporate water from the surface of plates according to the procedure described above. The eco dryer has been sold in a number of set-ups; the nozzles and the drying chamber are standard for all the dryers. However, the number of nozzles, channels, the capacity of the fan and the capacity of the heat exchanger differs for each customer. These factors depend on the available space, the position of the dryer and the specification for the rest of the plant. The nozzles are however always placed in pairs; one above and one under the plate, the number of pairs currently vary between 6 and 9.Energy costs and environmental issues are becoming more and more important for industry. This thesis aims to increase the depth of the knowledge of the dryer in order to make it more efficient, reducing the energy consumption per dried component. If the temperature of the air jets could be lowered by just 10 0C it would lead to a great decrease in energy consumption. This investigation was performed by using Comsol multiphysics combined with a theoretical approach, and the simulations were validated with experiments available in the literature. The simulations where focused on the nozzles of the dryer, a single nozzle was simulated as 2-dimensional with conditions as matching as possible to the actual dryer. The temperature of the plate is not constant from the beginning to the end of the dryer. However, during the process the plate spend very little time under each nozzle implying that the problem can be treated as being stationary for each nozzle. The calculations where done mainly for the dryer in a plant in Ruuki Häämenlinna, Finland; the results and data are, however, general and applicable for all dryers since the nozzles are the same for all dryers. The results indicates that the effect of the dryer in Häämenlinna could be tuned down and still be able to dry all the water at the highest plate speeds. This could be done by lowering the temperature of the air, by decreasing the effect of the heat exchanger. Another way would be to lower the speed of the air; which could be realized by decreasing the effect of the fan. For future constructions of dryers fewer nozzles, weaker fans and/or smaller heat exchangers could be considered to cut down material costs and increase efficiency. The results also showed which factors affect the drying rate of the plate. The speed of the plate is of great importance for example, since the amount of liquid on the plate is dependent on the plate speed and also because the nozzles will have lesser time to evaporate the water. The thickness of the plate has a lesser impact on the drying, if the drying was perfect the plate would not become any warmer during the process, instead every watt would go to evaporate the water.
Place, publisher, year, edition, pages
2013. , 51 p.
Teknik, Dysa, CFD, Comsol
IdentifiersURN: urn:nbn:se:ltu:diva-57092Local ID: dcb6db84-64d0-485a-a68f-abc58faaf0f6OAI: oai:DiVA.org:ltu-57092DiVA: diva2:1030479
Subject / course
Student thesis, at least 30 credits
Space Engineering, master's level
Validerat; 20130909 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved