Development of thermodynamic and reaction kinetic data on BaCl₂-NH₃ system with and without expanded natural graphite

Abstract

BaCl₂ as sorbent in ammonia-based solid sorption refrigeration systems offers advantage due to its lower heat of reaction. This article presents the experimentally obtained material, thermodynamic and kinetic properties of BaCl₂ and BaCl₂/expanded natural graphite composites suitable for refrigeration. Values of enthalpy and entropy of reaction of BaCl₂ obtained from the present study compare favorably with the literature reported values. Results showed that the reaction enthalpy and entropy of BaCl₂/expanded natural graphite are lower than that of pure BaCl₂. Using the measured reaction rate data and regression analysis, values of relevant kinetic coefficients for absorption and desorption are obtained for BaCl₂-NH₃ and BaCl₂-expanded natural graphite-NH₃. BaCl₂-expanded natural graphite is seen to offer favorable properties in terms of lower enthalpy of reaction and better kinetics. It is expected that this study which demonstrates the influence of additives on thermodynamic and reaction kinetics is useful in the synthesis and evaluation of new sorbents and additives suitable for refrigeration and air conditioning.