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Análise do desempenho energético do recuperador de calor em unidades de tratamento do ar novo
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| 2.36 MB | Adobe PDF |
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Abstract(s)
Este projeto foi concebido para estudar o desempenho do recuperador de calor em sistemas de unidades de tratamento de ar novo (UTAN), permitindo apresentar no final o modelo do comportamento térmico do mesmo face as necessidades do caso em estudo. O sistema UTAN é constituído por vários componentes, nomeadamente, filtros, ventiladores, recuperadores de calor e baterias de aquecimento e arrefecimento. Aplicou-se o modelo desenvolvido para realizar a simulação dinâmica do recuperador de calor em sistema UTAN ao longo do ano na base horaria com várias estratégias de controlo nomeadamente, velocidade dos escoamentos, temperatura do ar, número de ocupantes, comprimento do recuperador, espessura da placa do recuperador e espaçamento entre placas. Posteriormente, determinou-se a capacidade que as baterias de aquecimento e arrefecimento deverão ter de modo a conseguir suprir as necessidades da instalação
Para efeito de estudo do comportamento térmico e do desempenho do recuperador de calor recorreu-se a ensaios laboratoriais realizados num recuperador de pequena dimensão facultado pela empresa EVAC e aos dados do mesmo recuperador apresentado pela mesma empresa.
De modo a validar o programa desenvolvido, efetuou-se um estudo comparativo entre os valores obtidos através ensaios laboratoriais, valores apresentados pela empresa EVAC e valores obtidos através do método ε-NTU (efetividade -Número de Unidade de Transferência).
Todos cálculos foram efetuados numa folha de cálculo do software Excel desenvolvido para o efeito. A simulação foi efetuada para o bloco de Instituto Superior de Engenharia da Universidade do Algarve (Campus Penha).
Decidiu-se manter o sistema de ar condicionado tipo split existente no espaço. Segundo o programa desenvolvido face as condições de projeto do local em estudo, o recuperador dimensionado possuí 402 canais operando 401 placas com 0,1 cm de espessura e 0,39cm de espaçamento entre elas. A altura e largura da placa é de 1,58 m. O comprimento do recuperador é de 2 m. A velocidade do escoamento do fluido quente e frio é de 1,4 m/s. A efetividade e a diferença de pressão são aproximadamente 64% e 84 Pa respetivamente.
Em relação as baterias, através das correlações empíricas obteve-se a taxa de transferência de calor máxima necessária de 24, 707 kW verificada no mês de dezembro.
This project was designed to study the performance of the heat recovery system in dedicated outdoor air system (DOAS), allowing to present the model of the thermal behavior of the same face the needs of the case study. The DOAS system consists of several components, namely filters, fans, heat recovery and heating and cooling batteries. The model developed to perform the dynamic simulation of the DOAS heat recovery system throughout the year on a time basis was applied with various control strategies, namely, flow velocity, air temperature, number of occupants, recuperator length, the thickness of the recuperator plate and the spacing between plates. Subsequently, it was determined the capacity that the heating and cooling batteries should have in order to overcome needs of the installation. For the purpose of studying the thermal behavior and the performance of the heat recovery, it was used laboratory tests, carried out in a small-scale recuperator provided by the company EVAC and the data of the same recuperator presented by the same company. In order to validate the developed program, a comparative study was performed between the values obtained through laboratory tests, values presented by the EVAC company and values obtained through the ε NTU method (effectiveness-Number of transfer unit). All calculations were performed on an Excel spreadsheet developed for this purpose. The simulation was performed for the block of Instituto Superior de Engenharia of the University of Algarve (Penha Campus). It was decided to keep the split type air conditioning system in space. According to the program developed in view of the design conditions of the site under study, the dimensioned recuperator has 402 channels operating 401 plates with 0.1 cm thickness and 0, 39cm spacing between them. The height and width of the plate is 1.58 m. The length of the recuperator is 2 m. The flow velocity of the hot and cold fluid is 1.4 m/s. The effectiveness and the pressure difference are approximately 64% and 84 Pa, respectively. Regarding the batteries, through the empirical correlations, the maximum possible heat transfer rate necessary of 24, 707 kW was verified in the month of December
This project was designed to study the performance of the heat recovery system in dedicated outdoor air system (DOAS), allowing to present the model of the thermal behavior of the same face the needs of the case study. The DOAS system consists of several components, namely filters, fans, heat recovery and heating and cooling batteries. The model developed to perform the dynamic simulation of the DOAS heat recovery system throughout the year on a time basis was applied with various control strategies, namely, flow velocity, air temperature, number of occupants, recuperator length, the thickness of the recuperator plate and the spacing between plates. Subsequently, it was determined the capacity that the heating and cooling batteries should have in order to overcome needs of the installation. For the purpose of studying the thermal behavior and the performance of the heat recovery, it was used laboratory tests, carried out in a small-scale recuperator provided by the company EVAC and the data of the same recuperator presented by the same company. In order to validate the developed program, a comparative study was performed between the values obtained through laboratory tests, values presented by the EVAC company and values obtained through the ε NTU method (effectiveness-Number of transfer unit). All calculations were performed on an Excel spreadsheet developed for this purpose. The simulation was performed for the block of Instituto Superior de Engenharia of the University of Algarve (Penha Campus). It was decided to keep the split type air conditioning system in space. According to the program developed in view of the design conditions of the site under study, the dimensioned recuperator has 402 channels operating 401 plates with 0.1 cm thickness and 0, 39cm spacing between them. The height and width of the plate is 1.58 m. The length of the recuperator is 2 m. The flow velocity of the hot and cold fluid is 1.4 m/s. The effectiveness and the pressure difference are approximately 64% and 84 Pa, respectively. Regarding the batteries, through the empirical correlations, the maximum possible heat transfer rate necessary of 24, 707 kW was verified in the month of December
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Keywords
Unidade de tratamento de ar novo Ventilação Recuperador de calor