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Enhancing Electricity Generation by Reverse Electrodialysis
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A eletrodiálise inversa tem-se destacado como uma tecnologia promissora para a con-
versão de energia do gradiente de salinidade em eletricidade. No entanto, a sua eficiência é
fortemente influenciada pela geometria dos espaçadores, que afetam a distribuição do fluxo e
a resistência elétrica do sistema. Neste estudo, investigou-se a aplicação do efeito Coanda no
design dos espaçadores, com o objetivo de otimizar a circulação do fluido e melhorar o de-
sempenho da eletrodiálise inversa. Foram desenvolvidos e fabricados, através de impressão
3D, espaçadores inovadores que foram comparados com espaçadores comerciais, avaliando
parâmetros como a tensão de circuito aberto, resistência elétrica do módulo e densidade de
potência bruta. No total, foram testados oito espaçadores com diferentes geometrias e configurações.
Os resultados demonstraram que o espaçador Coanda 2x com grelha apresentou um
desempenho superior ao espaçador comercial com grelha. O valor máximo da tensão de circuito aberto atingido foi de 0.439 V, superior ao valor máximo de 0.434 V do espaçador comercial. Verificou-se ainda uma redução da resistência elétrica do módulo para 6.27 Ω e um au-mento da densidade de potência bruta para 1.53 × 10⁻³ W·m⁻², em comparação com os 10.56 Ω
e 9.50 × 10⁻⁴ W·m⁻² obtidos com o espaçador comercial. As melhorias na densidade de potência
relativamente ao espaçador comercial foram de 61,1% no modelo Coanda 2x, 57,9% no Coanda
3x e 51,6% no Coanda 4x com grelha. No entanto, a análise de fluxo realizada num módulo
transparente indicou que, apesar do efeito Coanda promover a adesão do fluido às superfícies
das estruturas do espaçador, o refluxo esperado não ocorreu devido à predominância do fluxo
ascendente, limitando o comportamento hidrodinâmico inicialmente projetado.
Este trabalho contribui para um melhor entendimento da influência da geometria dos
espaçadores na eficiência da eletrodiálise inversa, demonstrando que a otimização hidrodinâmica pode melhorar a conversão energética.
Reverse electrodialysis (RED) has gained attention as a promising technology for converting salinity gradient energy into electricity. However, its efficiency is highly dependent on the geometry of the spacers, which directly affect flow distribution and the system’s electrical resistance. This study investigated the application of the Coanda effect in spacer design, aiming to optimize fluid circulation and improve RED performance. Innovative spacers were developed and fabricated using 3D printing, and their performance was compared to that of commercial spacers. The evaluation considered open-circuit voltage (OCV), electrical resistance of the module, and gross power density. A total of eight spacers with different geometries and configurations were tested. The results showed that the Coanda 2x spacer with mesh exhibited superior performance compared to the commercial mesh spacer. The maximum open-circuit voltage recorded was 0.439 V, higher than the 0.434 V achieved by the commercial model. Additionally, the electrical resistance of the module was reduced to 6.27 Ω, and the gross power density increased to 1.53 × 10⁻³ W·m⁻², compared to 10.56 Ω and 9.50 × 10⁻⁴ W·m⁻² for the commercial spacer. The improvements in gross power density relative to the commercial reference were 61.1% for the Coanda 2x model, 57.9% for the Coanda 3x, and 51.6% for the Coanda 4x with mesh. However, flow analysis in a transparent module revealed that although the Coanda effect promoted fluid adhesion to the surfaces of the internal structures, the expected lateral recirculation did not occur due to the dominance of upward flow, which limited the intended hydrodynamic behaviour. This study contributes to a deeper understanding of how spacer geometry influences RED efficiency, demonstrating that hydrodynamic optimization can significantly enhance energy conversion performance.
Reverse electrodialysis (RED) has gained attention as a promising technology for converting salinity gradient energy into electricity. However, its efficiency is highly dependent on the geometry of the spacers, which directly affect flow distribution and the system’s electrical resistance. This study investigated the application of the Coanda effect in spacer design, aiming to optimize fluid circulation and improve RED performance. Innovative spacers were developed and fabricated using 3D printing, and their performance was compared to that of commercial spacers. The evaluation considered open-circuit voltage (OCV), electrical resistance of the module, and gross power density. A total of eight spacers with different geometries and configurations were tested. The results showed that the Coanda 2x spacer with mesh exhibited superior performance compared to the commercial mesh spacer. The maximum open-circuit voltage recorded was 0.439 V, higher than the 0.434 V achieved by the commercial model. Additionally, the electrical resistance of the module was reduced to 6.27 Ω, and the gross power density increased to 1.53 × 10⁻³ W·m⁻², compared to 10.56 Ω and 9.50 × 10⁻⁴ W·m⁻² for the commercial spacer. The improvements in gross power density relative to the commercial reference were 61.1% for the Coanda 2x model, 57.9% for the Coanda 3x, and 51.6% for the Coanda 4x with mesh. However, flow analysis in a transparent module revealed that although the Coanda effect promoted fluid adhesion to the surfaces of the internal structures, the expected lateral recirculation did not occur due to the dominance of upward flow, which limited the intended hydrodynamic behaviour. This study contributes to a deeper understanding of how spacer geometry influences RED efficiency, demonstrating that hydrodynamic optimization can significantly enhance energy conversion performance.
Descrição
Palavras-chave
reverse electrodialysis Coanda effect spacers flow optimization 3D printing