An analysis of a pulse combustion drying system

The paper presents a theoretical and experimental analysis of a pulse combu stion spray drying system. Measurements of the velocity flow field inside t he drying chamber and extensive tests on drying and water evaporation were carried out for various feed rates and operating parameters of the pulse co mbustor. Each test included the analysis of temperature distribution in the dryer, evaporation level and sprayed material structure. LDA and PDA techn iques were employed to determine the character of pulsating flow in the cha mber, amount of water evaporated and to perform a profound analysis of spra y structure. Experimental results show an intensive and efficient drying pr ocess. An attempt was made to perform theoretical predictions of velocity a nd temperature distribution in the drying chamber. The CFD technique was us ed to calculate time-dependent flow in the chamber. Results show vanishing velocity, pressure and temperature oscillations along the length of the dry ing chamber. Temperature oscillations decline faster than oscillations of p ressure and velocity. Satisfactory agreement between calculations and exper imental results was found in certain regions of the drying chamber. Discrep ancies might be caused by simplification of the system geometry and flow pa ttern which were assumed to perform calculations in reasonable time. (C) 19 99 Elsevier Science S.A. All rights reserved.