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Análise e otimização do funcionamento de uma UTA assitida por energia solar com enfoque na roda exsicante e respetivo controlador
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Resumo(s)
Vai-se tornando cada vez mais vital, atualmente, suprir as necessidades de consumo de energia, tais como as de eletricidade. Os sistemas de ar condicionado são responsáveis por uma grande parte desse consumo de eletricidade que se verifica no sector doméstico. De forma a suavizar os picos de consumo que se registam na época do verão, pode-se recorrer a sistemas de arrefecimento evaporativo exsicante (DEC, do inglês Desiccant Evaporative Cooling). Neste trabalho, em primeira instância, foram analisados vários dias no período de funcionamento da Unidade de Tratamento de Ar (UTA) do LNEG, desde 2003 até 2016 (atualidade). Os dias foram escolhidos segundo alguns critérios em termos de temperatura e de humidade, influenciando os processos de desumidificação e regeneração da roda exsicante e, consequentemente, o seu desempenho. Tentou estabelecer-se uma relação entre a velocidade de rotação da roda e a TCA. Esta acabou por não se verificar, no entanto o balanço de massa confirmou-se. Foram, desta forma, levados a cabo testes de análise de sensibilidade, para determinar a influência que variáveis como a temperatura, a humidade relativa e o caudal exercem na quantidade de água retida pela roda exsicante na conduta de entrada e cedida na conduta de saída, e, consequentemente, na transferência de conteúdo em água (TCA). Verificou-se que os caudais são as variáveis com mais influência na alteração das massas de água, principalmente o caudal de entrada, e as humidades relativas são as variáveis que mais influenciam a TCA. Por fim, compararam-se os caudais obtidos a partir da velocidade do ar com os caudais obtidos pelo sistema, fazendo-se assim novos testes, semelhantes aos últimos. Na maior parte dos casos, registou-se um aumento de todos os valores nas condutas de entrada e de saída de 33 e 26%, respetivamente. No entanto, para os caudais o aumento foi maior.
Is becoming increasingly vital to currently meet the power consumption needs, such as electricity’s. Air conditioning systems account for a large part of that consumption of electricity that occurs in households. In order to smooth consumption peaks that are registered in summer time, we can use desiccant evaporative cooling systems. In this work, first of all, were analyzed several days in the operation period of the air handling unit of LNEG, from 2003 to 2016 (today). The days were chosen according to certain criteria in terms of temperature and humidity, which are important to take into account, as they have a strong influence in the desiccant wheel’s performance. We tried to establish a relationship between the wheel rotation speed and water transfer content. This turned out not to be seen, however the mass balance was confirmed. Were then carried out sensitivity analysis tests to determine the influence of variables such as temperature, relative humidity and flow rate have on the amount of water held in the desiccant wheel inlet duct and given away in the outlet duct, and, hence, on the water content transfer. It was found that the flow rates are the variables with more influence in the change of water masses, particularly the incoming flow, and relative humidities are the variables that most influence the water content transfer. Finally, then, it was compared flow rates obtained from the air speed with flow rates obtained by the system, thus making new tests, similar to the latter. In most cases, there was an increase of all values in the inlet and outlet ducts of 33 and 26%, respectively. However, for the flow rate the increase was greater.
Is becoming increasingly vital to currently meet the power consumption needs, such as electricity’s. Air conditioning systems account for a large part of that consumption of electricity that occurs in households. In order to smooth consumption peaks that are registered in summer time, we can use desiccant evaporative cooling systems. In this work, first of all, were analyzed several days in the operation period of the air handling unit of LNEG, from 2003 to 2016 (today). The days were chosen according to certain criteria in terms of temperature and humidity, which are important to take into account, as they have a strong influence in the desiccant wheel’s performance. We tried to establish a relationship between the wheel rotation speed and water transfer content. This turned out not to be seen, however the mass balance was confirmed. Were then carried out sensitivity analysis tests to determine the influence of variables such as temperature, relative humidity and flow rate have on the amount of water held in the desiccant wheel inlet duct and given away in the outlet duct, and, hence, on the water content transfer. It was found that the flow rates are the variables with more influence in the change of water masses, particularly the incoming flow, and relative humidities are the variables that most influence the water content transfer. Finally, then, it was compared flow rates obtained from the air speed with flow rates obtained by the system, thus making new tests, similar to the latter. In most cases, there was an increase of all values in the inlet and outlet ducts of 33 and 26%, respectively. However, for the flow rate the increase was greater.
Descrição
Tese de mestrado integrado, Engenharia de Energia e do Ambiente, Universidade de Lisboa, Faculdade de Ciências, 2016
Palavras-chave
Arrefecimento evaporativo exsicante Unidade de tratamento de ar Desumidificação Regeneração Roda exsicante Teses de mestrado - 2016