The influence of evaporation on the cooling small cup of hot water

This study investigates the cooling of hot water in a standard small paper cup, commonly used for serving coffee or tea. The cup height is 105 mm, and the paper wall thickness is 0.45 mm. Water properties and density are treated as temperature-dependent. A three-dimensional (3D) computational fluid dynamics (CFD) model, coupled with a large eddy simulation (LES) turbulence framework, predicts convection and conjugate heat transfer throughout the cooling process. A key contribution is the implementation of advanced boundary conditions for both the cup’s sidewall and the water-air interface. A custom submodel integrated into the commercial 3D CFD code captures heat losses at these surfaces by accounting for thermal radiation, natural convection, and, at the free surface, evaporative cooling. The time history of the simulated sidewall temperatures at three vertical locations closely matches published experimental measurements, confirming the model’s accuracy. Results highlight the critical role of evaporative cooling: omitting this mechanism significantly underpredicts the cooling rate. The potential influence of Marangoni convection is also evaluated and discussed. • Cooling of hot water in a standard small cup made of paper. • 3D CFD LES model have been used for the prediction of cooling processes. • Thermal radiation, natural convection and water evaporation cooling. • Very good agreement with experimental data.