Propriedades da solução Amônia-Água(NH3-H2O) - Refrigeração por absorção
Autor: Eddie Liberato | Publicado: 2013-05-18T22:01:00-03:00


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Essa postagem é uma contribuição para aqueles que assim como eu passaram por dificuldades ao ler o diagrama de equilíbrio Amônia-Água (NH3-H2O) no momento de projetar ciclos de refrigeração por absorção.



&nbsp;

Diagrama de equilíbrio NH3-H2O&nbsp;

fonte: ASHRAE 

&nbsp;&nbsp;&nbsp;&nbsp;

&nbsp;&nbsp;&nbsp; Como o diagrama apresenta um emaranhado de linhas com muita informação combinada em apenas uma figura fica fácil cometer algum erro no momento da leitura. Para diminuir a chance de cometer erros e melhorar a acurácia na obtenção da informação, eu busquei na literatura especializada as equações pertinentes para os cálculos. Seguem abaixo as equações:



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Fonte: PÁTEK. J.; KLOMFAR, J. Simple
functions for fast calculations of selected thermodynamics properties of the
ammonia-water system. Internationa
Journal of Refrigeration, 18(4), pp. 228-234, 1995. &nbsp;


&nbsp;T=temperatura; P=pressão; x=fração molar de amônia(NH3) para mistura no estado liquido; y=fração molar de amônia(NH3) para mistura no estado de vapor



&nbsp;

&nbsp;Equação da temperatura em função da pressão e fração molar de amônia(NH3) para mistura no estado liquido





&nbsp; Equação da entalpia em função da temperatura e fração molar de amônia(NH3) para mistura no estado liquido





&nbsp;



&nbsp; Equação da temperatura em função da pressão e fração molar de amônia(NH3) para mistura no estado de vapor



&nbsp;

&nbsp; Equação da entalpia em função da temperatura e fração molar de amônia(NH3) para mistura no estado de vapor



&nbsp;&nbsp;&nbsp;&nbsp; Apesar de completamente empíricas as equações apresentam um excelente resultado para pressões até 30bar. 



&nbsp;&nbsp;&nbsp;&nbsp; Setar as equações é um trabalho razoável, no caso da HP50g precisa conhecer alguns macetes da calculadora.&nbsp; Entretanto usuarios da HP50g podem baixar o arquivo que compartilho nesse Link