title: Effect of the load size on the efficiency of microwave heating under stop flow and continuous flow conditions.
abstract: A novel heating efficiency analysis of the microwave heated stop-flow (i.e. stagnant liquid) and continuous-flow reactors has been presented. The thermal losses to the surrounding air by natural convection have been taken into account for heating efficiency calculation of the microwave heating process. The effect of the load diameter in the range of 4-29 mm on the heating efficiency of ethylene glycol was studied in a single mode microwave cavity under continuous flow and stop-flow conditions. The variation of the microwave absorbing properties of the load with temperature was estimated. Under stop-flow conditions, the heating efficiency depends on the load diameter. The highest heating efficiency has been observed at the load diameter close to the half wavelength of the electromagnetic field in the corresponding medium. Under continuous-flow conditions, the heating efficiency increased linearly. However, microwave leakage above the propagation diameter restricted further experimentation at higher load diameters. Contrary to the stop-flow conditions, the load temperature did not raise monotonously from the inlet to outlet under continuous-flow conditions. This was due to the combined effect of lagging convective heat fluxes in comparison to volumetric heating. This severely disturbs the uniformity of the electromagnetic field in the axial direction and creates areas of high and low field intensity along the load Length decreasing the heating efficiency as compared to stop-flow conditions.
authors.affiliation: Laboratory of Chemical Reactor Engineering, Eindhoven University of Technology, P.O.Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Narendra G
authors.initials: NG
authors.lastname: Patil
authors.affiliation: School of Chemistry and Chemical Engineering, Queen's University Belfast, Stranmillis Road, Belfast BT9 5AG, United Kingdom.
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Rebrov
authors.affiliation: Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Abo Akademi University, Biskopsgatan 8, FIN-20500 Turku/Abo, Finland.
authors.forename: Kari
authors.initials: K
authors.lastname: Eränen
authors.affiliation: Laboratory of Chemical Reactor Engineering, Eindhoven University of Technology, P.O.Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Faysal
authors.initials: F
authors.lastname: Benaskar
authors.affiliation: Laboratory of Chemical Reactor Engineering, Eindhoven University of Technology, P.O.Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Meuldijk
authors.affiliation: Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Abo Akademi University, Biskopsgatan 8, FIN-20500 Turku/Abo, Finland.
authors.forename: Jyri-Pekka
authors.initials: JP
authors.lastname: Mikkola
authors.affiliation: Laboratory of Chemical Reactor Engineering, Eindhoven University of Technology, P.O.Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Volker
authors.initials: V
authors.lastname: Hessel
authors.affiliation: Laboratory of Chemical Reactor Engineering, Eindhoven University of Technology, P.O.Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Lumbertus A
authors.initials: LA
authors.lastname: Hulshof
authors.affiliation: Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Abo Akademi University, Biskopsgatan 8, FIN-20500 Turku/Abo, Finland.
authors.forename: Dmitry Yu
authors.initials: DY
authors.lastname: Murzin
authors.affiliation: Laboratory of Chemical Reactor Engineering, Eindhoven University of Technology, P.O.Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Jaap C
authors.initials: JC
authors.lastname: Schouten
mesh_terms: D003198:Computer Simulation; D004735:Energy Transfer / Q000528:radiation effects*; D019855:Ethylene Glycol / Q000737:chemistry* / Q000528:radiation effects*; D006361:Heating / Q000379:methods*; D008872:Microwaves; D008956:Models, Chemical; D011829:Radiation Dosage; D012212:Rheology / Q000379:methods*; D012996:Solutions / Q000737:chemistry / Q000528:radiation effects
chemical_list: D012996:Solutions; D019855:Ethylene Glycol