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Abstract(s)
As costas áridas do mundo carecem de fontes naturais de água doce, havendo neste caso alta dependência na dessalinização da água, processo de alto consumo energético e normalmente alimentado a combustíveis fósseis. Esta é uma realidade vivida principalmente nas comunidades isoladas e com baixo rendimento económico. O aproveitamento da radiação solar como fonte de energia para o processo de dessalinização via destilação solar parece ser uma boa alternativa. Isto porque a destilação solar opera com base em tecnologias relativamente simples, podendo ser operada por mão de obra pouco qualificada. Com base em equações que expressam as relações básicas de transferência de calor e massa num destilador solar, foi desenvolvido um modelo matemático que permite estimar a quantidade de água produzida por destilação solar, para além de outros parâmetros que caracterizam a sua operação. Os cálculos foram feitos para o período de um ano típico, tendo como base de dados um ficheiro climático. Foi obtido uma produção anual que varia entre 0,51 e 0,56 m3 de água destilada por m2 de área de captação solar. Foram analisadas quatro propostas de construção de destiladores solares, com o objetivo de efetuar um estudo de viabilidade económica dos mesmos, para a realidade de Cabo Verde. Das quatro propostas apresentadas, todas apresentaram valores negativos tanto do VAL, como da TIR e apresentando também um período de retorno do investimento superior ao tempo de vida útil do equipamento. Portanto, nenhuma das soluções mostrou ser viável economicamente. O custo de construção varia entre 15 038,02 ECV e 20 040,77 ECV, o custo da água produzida varia entre 2 199,38 ECV e 2 644,72 ECV, o período de retorno do investimento varia entre 26 e 32 anos, o VAL varia entre -9 779,21 ECV e -15 535,98 ECV, e o TIR varia entre -7% e -10%. Foi também estimada a quantidade de gases de efeito de estufa (em CO2e) que a utilização do processo de destilação solar permite poupar em alternativa ao processo de osmose inversa, sendo que foi obtido um valor anual de 28,6 kgCO2e/m2.
The arid coasts of the world lack natural sources of fresh water, where there is a high dependence on water desalination, a process of high energy consumption and normally fueled by fossil fuels. This is a reality lived mainly in isolated communities with low economic income. The use of solar radiation as a source of energy for the desalination process via solar distillation seems a good alternative. This is due to the fact that solar distillation operates on relatively simple technologies and can be operated by unskilled labor. Based on equations that express the basic heat and mass transfer relations in a solar distiller, a mathematical model was developed to estimate the amount of water produced by solar distillation, in addition to other parameters that characterize its operation. The calculations were made for a typical one-year period using a climatic file as a database. An annual production ranging from 0.51 to 0.56 m3 of distilled water per m2 of solar catchment area was obtained. Four proposals for the construction of solar distillers were analyzed, with the objective of making a study of their economic viability, for the reality of Cape Verde. Of the four proposals presented, all presented negative values of both NPV and IRR and presented payback period longer than the useful life of the equipment. Therefore, none of the solutions proved to be economically viable. The cost of construction ranges from 15 038.02 ECV to 20 040.77 ECV, the cost of water produced varies from ECV 2 199.38 to ECV 2 644.72, the payback period varies from 26 to 32 years, NPV ranges from -9 779.21 ECV to -15 535.98 ECV, and IRR ranges from -7% to -10%. It was also estimated the amount of greenhouse gases (in CO2e) that the use of the solar distillation process allows to save as an alternative to the reverse osmosis process, and an annual value of 28.6 kgCO2e/m2 was obtained.
The arid coasts of the world lack natural sources of fresh water, where there is a high dependence on water desalination, a process of high energy consumption and normally fueled by fossil fuels. This is a reality lived mainly in isolated communities with low economic income. The use of solar radiation as a source of energy for the desalination process via solar distillation seems a good alternative. This is due to the fact that solar distillation operates on relatively simple technologies and can be operated by unskilled labor. Based on equations that express the basic heat and mass transfer relations in a solar distiller, a mathematical model was developed to estimate the amount of water produced by solar distillation, in addition to other parameters that characterize its operation. The calculations were made for a typical one-year period using a climatic file as a database. An annual production ranging from 0.51 to 0.56 m3 of distilled water per m2 of solar catchment area was obtained. Four proposals for the construction of solar distillers were analyzed, with the objective of making a study of their economic viability, for the reality of Cape Verde. Of the four proposals presented, all presented negative values of both NPV and IRR and presented payback period longer than the useful life of the equipment. Therefore, none of the solutions proved to be economically viable. The cost of construction ranges from 15 038.02 ECV to 20 040.77 ECV, the cost of water produced varies from ECV 2 199.38 to ECV 2 644.72, the payback period varies from 26 to 32 years, NPV ranges from -9 779.21 ECV to -15 535.98 ECV, and IRR ranges from -7% to -10%. It was also estimated the amount of greenhouse gases (in CO2e) that the use of the solar distillation process allows to save as an alternative to the reverse osmosis process, and an annual value of 28.6 kgCO2e/m2 was obtained.
Description
Keywords
Dessalinização Radiação Solar Destilação Solar Simulação Computacional Cabo Verde Desalination Solar Radiation Solar Distillation Computational Simulation Cape Verde