HEAT TRANSFER ANALYSIS FOR THE HYDRAULIC CIRCUIT OF AN EXPRESSO-COFFEE MACHINE

An Espresso-Coffee Machine supplies water whose temperature must be confined within a narrow range in different operating conditions; this requires an accurate design at the component as well as the system level. The objective of this study is to develop a mathematical model to analyze the performance of the heating circuit of such a machine, aiming to capture the main operating characteristics of the system with maximum simplicity. The governing equations of the model were solved using the finite difference technique, and the results were compared with experimental data. The study found that the temperature of the water injected into the coffee filter, during the active phase, initially varies significantly but stabilizes to a satisfactory range after a brief startup period. The first numerical results indicate a good agreement between the predictions of the model and the experimental data, demonstrating that the main characteristics of the heating process can be captured using a simple model based on lumped parameters. This study may inform the design and optimization of espresso coffee machines, ensuring they deliver high-quality coffee efficiently.