Table of Contents
International Journal of Microwave Science and Technology
Volume 2011, Article ID 264249, 10 pages
Research Article

Influence of System Variables on the Heating Characteristics of Water during Continuous Flow Microwave Heating

Department of Food Science and Agricultural Chemistry, Macdonald Campus of McGill University, 21 111 Lakeshore Road, Ste. Anne de Bellevue, Monterial, QC, Canada H9X 3V9

Received 10 April 2011; Revised 6 July 2011; Accepted 15 August 2011

Academic Editor: Samir Trabelsi

Copyright © 2011 Hosahalli S. Ramaswamy and Manguang Lin. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A domestic microwave oven (1000 W) was modified to permit the continuous flow of liquids run through a helical coil centrally located inside the oven cavity. Heating characteristics were evaluated by measuring inlet and outlet temperatures of coil as a function of system variables. The influence of number of turns, coil diameter, tube diameter, pitch and initial temperature were evaluated at different flow rates. The average residence time of water was computed by dividing the coil volume by the volumetric flow rate. The influence of Dean number was evaluated. Results from this study showed that (1) higher number of turns resulted in lower heating rate, lower temperature fluctuations, higher exit temperature and longer time to achieve temperature equilibrium; (2) larger tube or coil diameter gave larger coil volume causing the heating rate to decrease; (3) faster flow rates resulted in lower exit temperatures, lower temperature fluctuation, higher Dean number and slightly higher heating rate; (4) higher initial temperatures resulted in higher exit temperatures; (5) higher Dean number resulted in more uniform heating and slightly higher heating rate. Overall, the coil volume was the more dominant factor affecting heating rate as compared with flow rate and Dean number.