With the increasing pressure of providing reliable potable water in a sustainable way, it is important to understand water phase change phenomena (condensation and evaporation) as the water phase change is involved in many processes such as membrane distillation and solar still which can be a feasible choice of supplementing the present potable water access. In the present thesis, we first elucidate the role of wettability of water condensation substrate by combining the droplet growth dynamics and droplet population evolution. The results show that wettability has a negligible effect on water condensation rate in an atmospheric environment. After confirming the role of substrate wettability, we provide a quantitative analysis of the effect of substrate geometry on water condensation in the atmospheric environment. The analysis can help to predict the efficiency of water condensation rate with a given substrate of a certain geometry with the aid of computational simulation tools. The results show that water condensation can be increased by 40% by rationally designing the geometry of the condensation surface. However, the condensation rate in the atmospheric environment is relatively slow due to the presence of non-condensable gas. In order to increase the condensation rate, a relatively pure vapor environment is desired, in which condensed water will be the major heat transfer barrier. Coalescence induced jumping of condensed droplets on superhydrophobic surfaces is an interesting phenomenon to help faster removal of condensed droplets. However, it is still not clear how to optimize the overall heat transfer efficiency by condensation on such surfaces. We observed an interesting phenomenon on a superhydrophobic nano-cones array, on which water preferentially condenses within larger cavities among the nanocones. Droplets growing form larger cavities have larger growth rate. This finding can possibly provide a solution to optimizing heat transfer efficiency. Finally, a nylon-carbon black composite is prepared by electrospinning to enhance water evaporation under solar radiation. The composite shows an interesting light absorption property. In a wet state, the composite can absorb around 94% of the incident sunlight. The composite also shows strong mechanical and chemical stability. Thus, the composite is considered to be a practical candidate to be applied in the solar distillation process.

Made available in DSpace on 2016-04-28T18:24:13Z (GMT). No. of bitstreams: 1 Valeria Lopes.pdf: 4515075 bytes, checksum: 560e903f99d6fc9cd36ca29e491b8a03 (MD5) Previous issue date: 2009-11-17 / Secretaria da Educação do Estado de São Paulo / This study aims at understanding if the teacher-researcher s participation in the preparation of the teaching unit in question could bring contributions to students learning at the same time disclosing possible reasons for those contributions. The importance of this research lies in the possibility to clearly comprehend the role of a teaching unit in the English teaching-learning process, from the teacher s and the students point of view. As theoretical bases, this investigation uses, among other concepts, the socio-historical-cultural view of teaching-learning (Vigotski, 1930/1998, 1934/2005), Parâmetros Curriculares Nacionais Língua Estrangeira (Brasil, 1998) and criteria for the production and evaluation of materials (Cunningsworth, 1984; Graves, 1996, 2000). Methodologically, it is a case study within the interpretive qualitative paradigm that for data collection makes use of questionnaires, reflective diaries, interviews and the final production of students resulting from the unit. The participants are the teacher-researcher and eight students from the 1st grade Ensino Médio , of a state school in the city of São Paulo. The results indicated that the teacher-researcher s participation in the preparation of the material brought contributions, as she felt better prepared to use the material in class and consequently the students learning was more adequately conducted / O objetivo deste trabalho é compreender se o fato da professora-pesquisadora ter participado da elaboração da unidade didática em estudo poderia trazer contribuições para a aprendizagem dos alunos e também descobrir as razões que poderiam levar a tais contribuições. A importância da presente pesquisa reside na possibilidade de aprofundar o entendimento acerca do papel de uma unidade didática no processo de ensino-aprendizagem de língua inglesa, tanto do ponto de vista do professor quanto dos alunos. Como embasamento teórico, esta pesquisa utiliza, entre outros conceitos, a visão sócio-histórico-cultural de ensino-aprendizagem (Vigotski, 1930/1998, 1934/2005), os Parâmetros Curriculares Nacionais Língua Estrangeira (Brasil, 1998) e critérios para a produção e avaliação de material didático (Cunningsworth, 1984; Graves, 1996, 2000). Metodologicamente, trata-se de um estudo de caso inserido no paradigma qualitativo interpretativista, que se utiliza de questionários, diários reflexivos, entrevistas e da produção final dos alunos, fruto da unidade, para coletar os dados. Os participantes são a professora-pesquisadora e oito alunos de um 1º Ensino Médio de uma escola pública estadual em um bairro do município de São Paulo. Os resultados indicaram que a participação da professora-pesquisadora na elaboração da unidade didática trouxe contribuições, pois fez com que ela se sentisse mais preparada para utilizar o material em sala e a aprendizagem dos alunos fosse conduzida de maneira mais adequada