Iw. Turner et al., A NUMERICAL INVESTIGATION OF COMBINED MICROWAVE AND CONVECTIVE DRYINGOF A HYGROSCOPIC POROUS MATERIAL - A STUDY BASED ON PINE WOOD, Chemical engineering research & design, 76(A2), 1998, pp. 193-209
In this paper a numerical investigation of the combined microwave and
convective drying of a hygroscopic porous material is undertaken. A co
mprehensive mathematical model has been developed and a numerical code
known as Wood1D implemented so that the impact of dielectric heating
on the overall drying kinetics can be analysed. The code, which provid
es the analysis of the time evolution of moisture content, temperature
, pressure and microwave power distributions, is an effective tool whi
ch can be used to obtain a better understanding of the underlying phys
ics of the drying process at a fundamental level. Furthermore, the sim
ulations can be used to identify key model parameters so that a subseq
uent sensitivity study can be carried out in order to establish the ef
fects that these parameters have on the performance of combined microw
ave and convective drying. Once the model has been fine tuned to the d
rying engineer's specifications, the code can be used to assist with t
he optimization of a given dryer design. In this work the model is tes
ted and validated against experimental data for both convective drying
and combined microwave and convective drying of pine wood. The drying
times, drying rates and efficiencies, together with the related moist
ure, temperature, pressure and power profiles will be compared and ana
lysed for a number of combinations of convective and microwave energy.
It is hoped that the knowledge gained from this study can be used to
assist with the evaluation of the overall economic feasibility of usin
g combined microwave and convective drying processes.