Energetic Analysis using theoretical modeling and the characteristic equation method in a small absorption chiller with LiBr/H2O

Alvaro Antonio Ochoa Villa, José Ângelo Peixoto da Costa, Carlos Antonio Cabral dos Santos


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.



absorption chiller; characteristic equation; lithium bromide/water.

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DOI: http://dx.doi.org/10.4025/actascitechnol.v40i1.34969

ISSN 1806-2563 (impresso) e ISSN 1807-8664 (on-line) e-mail: actatech@uem.br


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