Detailed Simulation of Fluid Dynamics and Heat Transfer in Coffee Bean Roaster

This work presents finite-element-method-based simulations of fluid dynamics and heat transfer in a practical coffee bean roaster. The source of heat and air speed at the exhaust window were identified as critical operating parameters affecting the temperature and air speed distribution in the roaster. Quantitative analysis was conducted to elucidate the relationships among the power of heat source, air speed at the exhaust window, temperature and air speed profiles within the roaster chamber. The resulting air speed distribution values were then used to simulate the transfer of heat between the coffee beans and the surrounding air. Highly unevenly temperature distributions were observed in the coffee beans in the first 60 s of the roasting process. Nonetheless, between 100 and 720 s, the temperature in the coffee beans became increasingly uniform as it increased monotonically to approximately 200 degrees C. Practical ApplicationsRoasting conditions (air speed, temperature profile and duration) play a critical role in the resulting aroma and flavor of roasted coffee beans. We developed a methodology for the predictions of the air speed and temperature within the roaster. This methodology developed in this work could be used in optimizing the design of a coffee bean roaster as well as the roasting conditions.