Two-dimensional CFD modeling of the heat and mass transfer process during sewage sludge drying in a solar dryer
The paper presents key assumptions of the mathematical model which describes heat and mass transfer phenomena in a solar sewage drying process, as well as techniques used for solving this model with the Fluent computational fluid dynamics (CFD) software. Special attention was paid to implementation of boundary conditions on the sludge surface, which is a physical boundary between the gaseous phase - air, and solid phase - dried matter. Those conditions allow to model heat and mass transfer between the media during first and second drying stages. Selection of the computational geometry is also discussed - it is a fragment of the entire drying facility. Selected modelling results are presented in the final part of the paper.
Krawczyk P.: Research of the Thermal-hydraulic Processes in Sewage Sludge Solar Dryer. PhD thesis, Division of Power Machines and Devices, Institute of Heat Engineering, Warsaw University of Technology, Warsaw 2008 (in Polish).
Badyda K., Krawczyk P.: Research of heat and flow processes in a solar waste-water sludge dryer. Polish J. Environmental Studies 17(2008), 3A, 28-32.
Badyda K., Krawczyk P.: Modelling of heat and flow processes in thin layer solar sludge dryer. Impact of using mixing baffles on the basic parameters of the dryer. Polish J. Environmental Studies 20(2011), 4A, 185-189.
Badyda K., Krawczyk P.: Modelling of thermal and flow processes in solar waste-water sludge dryer with supplementary heat from external sources. Prace Naukowe Politechniki Warszawskiej ser. Konferencje 26(2009), 17-24. Oficyna Wydawnicza Politechniki Warszawskiej, Warsaw 2009 (in Polish).
Strumiłło Cz.: Fundamentals of Theory and Techniques of Dryin.: WNT, Warsaw 1983 (in Polish).
Katsiris N., Koszeli-Katsiris A.: Bound water content of biological sludges in relation to filtration and dewatering. Water Res 21(1987), 1319-1327.
Stolarek P., Ledakowicz S., Pakowski Z., Grębowski M.: Determination of diffusivity of water in the sludge by means of thermogravimetry. Przegląd Papierniczy 12(2003), 745-748 (in Polish).
Arlabosse P., Chavez S., Prevot C.: Drying of municipal sewage sludge: from a laboratory scale batch indirect dryer to the paddle dryer. Brazilian J. Chemical Engineering 22(2005), 02, 227-232.
Dewil R., Baeyens J., Neyens E.: Fenton peroxidation improves the drying performance of waste activated sludge. J. Hazardous Materials B117(2005) 161-170.
Rup K.: Transfer Processes of Pollution in the Environment. WNT, Warsaw 2006 (in Polish).
Malczewski J., Piekarski M.: Transport of Momentum Energy and Mass. Wydawnictwa Politechniki Warszawskiej, Warsaw 1984 (in Polish).
Wiśniewski S., Wiśniewski T.: Heat Transfer. WNT, Warsaw 2000 (in Polish).
Krawczyk P., Szczygieł J., Szwarc W.: Solar drying of sewage sludge, the project and initial operating experience. In: Proc. Conf. "Integrated intelligent systems of utilisation of renevable energy", Częstochowa 2005 (in Polish). Available at http://www.is.pcz.czest.pl/hosting/kie/konf.html http://www.is.pcz.czest.pl/hosting/kie/konf.html