Heat transfer analysis of a microwave reactor using computational fluid dynamics for polymer recycling

Microwave heating has emerged as an attractive heat source for polymer recycling processes such as alcoholysis. The rapid localized heating allows for the reaction time for alcoholysis to be decreased from hours to minutes. Despite this, microwave heating does suffer from a shortcoming which is also present in conventional heating i.e., nonuniformity of the temperature distribution. In order to optimize the design of the microwave reactor for large-scale polymer recycling via alcoholysis, it is essential to understand and predict the temperature distribution inside the reactor. This can be achieved through numerical simulations of microwave heating and the hydrodynamics of the system. This study develops a microwave heating model by one-way coupling high-frequency electromagnetism, heat transfer, and fluid dynamics utilizing the finite element and finite volume methods by conducting two commercial packages i.e., ANSYS HFSS, and FLUENT. The numerical simulation demonstrates the reactor’s response to the applied circumstances, exhibiting aprogressive rise in temperature as the reaction time increases. These findings highlight the significance of agitation in ensuring consistent temperature distribution within the reactor. Microwave irradiation is employed to selectively heat the reaction media, resulting in accelerated reactions in comparison to conventional heating techniques. The temperature in a 2 L reactor is expected to increase by 150 ºC during a short span of 25 minutes, leading to a substantial reduction in the reaction time for alcoholysis.