Chinese Journal of Chemical Engineering ›› 2019, Vol. 27 ›› Issue (10): 2510-2517.doi: 10.1016/j.cjche.2019.01.013

• Chemical Engineering Thermodynamics • Previous Articles     Next Articles

Desorption isotherms and isosteric heat of anaerobic fermentation residues

Tibor Poós, Viktor Szabó   

  1. Department of Building Services and Process Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Bertalan Lajos u. 4-6, H-1111 Budapest, Hungary
  • Received:2018-09-03 Revised:2018-11-12 Online:2019-10-28 Published:2020-01-17
  • Contact: Tibor Poós, Viktor Szabó;

Abstract: This paper presents the equilibrium desorption isotherms and the isosteric heat of sorption of a mixture containing mechanically dewatered fermentation residue (obtained from a blend of chicken, swine and cattle manure) used in biogas plants and corn spoiled silage in a ratio of 2:1. The moisture desorption isotherms of the fermentation residue were determined at 32℃, 40℃ and 80℃ and in the relative humidity range of 0.057/1 using static gravimetric method. Mathematical equations were used to analyze the desorption data of Modified Henderson, Modified Halsey, Modified Oswin, Modified Chung-Pfost and Modified GAB models. The constants of the model equations were calculated by non-linear regression analysis. The Modified Henderson model fitted to the desorption isotherm data well. Using the proposed function, the final moisture content of the material can be determined as long as it can be dried in infinite time with the drying gas in the given conditions. The isosteric heat of desorption was calculated by using the Modified Henderson model in the studied temperature range based on the Clausius-Clapeyron equation. The isosteric heat varied between 46 kJ·mol-1 and 67 kJ·mol-1 at moisture levels 1.91 < Xe < 4.05 kgH2O·kgdP-1 for the material.

Key words: Desorption, Equilibrium, Model, Measurement, Isosteric heat