A theoretical study on the use of microwaves in reducing energy consumption for an endothermic reaction: Role of metal coated bounding surface

This work presents a theoretical analysis on savings of energy during an endothermic reaction under microwave heating compared to conventional heating and shows the use of metal coated bounding surface to enhance the energy savings in otherwise low saving zones. Main thrust of this work is the quantification of energy savings for various probable microwave heating scenarios that may arise either due to varying reactor dimension (2L) over thin, intermediate and thick regimes or due to varying dielectric properties of the reactor. The analysis considers detailed transport equations in conjunction with Helmholtz equation for microwave propagation within a semiinfinite batch reactor. Simulations show that use of microwave can significantly save energy (as high as 60%) depending on reactor configuration. Simulations also show efficient use of metal coated bounding surface to enhance energy savings for reactors with 2L/λeff = 0.5n−0.25, where n = 1, 2, 3… and λeff is wavelength of microwave within the reactor. The enhancement is found to be 2 and 1.5 times at 2L/λeff = 0.25 and 0.75, respectively. Various regions of efficient use of metal coated bounding surface for different microwave heating scenarios have been identified in a series of master curves.