Energetic Analysis using theoretical modeling and the characteristic equation method in a small absorption chiller with LiBr/[H.sub.2]O/Analise energetica de um chiller de absorcao de LiBr/[H.sub.2]O de pequeno porte utilizando modelagem teorica e o metodo equacao caracteristica

This paper sets out to examine a small absorption chiller that uses the pair LiBr/H2O with a 4.5 kW nominal capacity, using theoretical modeling and the characteristic equation method. The idea is to compare two ways of simulating and evaluating absorption systems by analyzing the temperatures and flow rates of external hot, chilled and cold water circuits, as well as the values of the overall heat transfer coefficients of each component. Energetic analysis is based on conserving mass and energy by taking into consideration the overall heat transfer coefficients and their respective areas via the UA products of the 5 components of the absorption chiller. The characteristic equation method is based on Duhring's rule of the internal temperature which is founded on saturation mean temperatures and the Duhring coefficient (B). The results of comparing the activation of thermal power and the cooling capacity of the Rotartica absorption chiller, obtained by theoretical modeling and from the characteristic equation values, were good since the mean relative errors found were 4% lower for most of the operating conditions examined. Keywords: absorption chiller; characteristic equation; lithium bromide/water. Este trabalho tem como objetivo o estudo energetico de um chiller de absorcao de pequeno porte que utiliza o par LiBr/[H.sub.2]O de 4,5 kW atraves da modelagem teorica e o metodo da equacao caracteristica. A ideia e comparar duas formas de avaliar os sistemas de absorcao visando as temperaturas e vazoes dos circuitos externos de agua fria, quente e gelada, assim como os valores dos coeficientes globais de cada componente. A analise energetica esta baseada na conservacao da massa e energia levando em consideracao os coeficientes globais de transferencia de calor e suas respectivas areas atraves dos produtos UA dos 5 componentes do chiller de absorcao. O metodo da equacao caracteristica baseia-se na regra de Duhring relacionando as temperaturas internas de saturacao em funcao das temperaturas medias externa e o coeficiente de Duhring (B). A comparacao dos resultados da energia de ativacao termica e da capacidade de refrigeracao do chiller de absorcao Rotartica, obtido pela modelagem teorica e pelo metodo da equacao caracteristica foi boa ja que os erros relativos medios encontrados foram inferiores em 4% para a maioria das condicoes de operacao. Palavras-chave: chiller de absorcao; equacao caracteristica; brometo de litio/agua.