REDISEÑO DE DESHIDRATADORES SOLARES INCORPORANDO RECIRCULACIÓN DE AIRE Y EVALUACIÓN EXPERIMENTAL DE MEJORAS

Abstract

Interest by new solar energy projects in Chile, and the growingneed for sustainable energy in agriculture, plus the increasing globaldemand for dryed food. IT's been developed equipment and transportablemodules, oriented to agricultural SME's with small-scale productionsthat can supply that need.This Thesis main objective is to redesign two modules of solardryers, incorporate air recirculation used and released into the environment, which still has a thermal potential energy that can beused. Therefore, it is to study, through experimentation the currentoperation of two solar dryers modules created by the Department ofMechanical Engineering of the Universidad Tecnica Federico SantaMaría, which by, forced convection and the concept of active ceiling,they reach their objetive. Based on this, its raises and evaluated twodierent types of hot air recirculation and are nally compared withexisting models.In relation of the modifications, only the \single family" (DSU)dryer suers major structural changes as necessary to redesign theexisting model, while the \container" type dryer (DS) recirculationis incorporated and its structure does not undergo major changes.According with the obtained results, it concludes that hot ait recirculationcan be used on solar models dryers that function by forcedconvection, their efficiency in the drying process as well as in the manifoldis greater than the existing design, Being the recirculation systemType A more beneficial, since improves the existing model by 10C,contributing an increase of 15 to 20ºC compared to the ambient temperature,besides allowed by the proposed hermetic drying chamber,the relative humidity inside of it is always in a favorable condition tothe drying process, reaching 10-15% under ambient humidity duringthe day and at night this value is maintained to 10% lower. Whit thisdata and comparing it with the recirculation system Type B, whichalso contributes with not as significantly higher temperatures and lowerhumidity percentages as the other design, its determined that theType A design can be used on low radiation periods. For both designs,the drying times were reduced in average of two days, reachingon Type A recirculation system betters results.Experimentally, its verified that the incorporation of recirculationsucceeds in reducing the drying times at least in one day comparingby the existing model. With this, is achieved to generate a final designfor both modules where recirculation its incorporated