Influencia del modelo de densidad en el modelado numérico de convección natural cercano al punto de inversión de densidad del agua durante la transferencia de calor conjugado transitoria

Pasteurization of dairy products using the low temperature, long time (LTLT) method is a simple and cost-effective heat treatment that requires minimal investment, making it suitable for small-scale milk production. However, the cooling stage of pasteurization is often overlooked and rarely considered in process design. This study aims to evaluate heat transfer during the cooling phase of a batch pasteurization process, modeled as two concentric, vertically enclosed cylinders filled with water. For the experiment, the outer enclosure was maintained between 2 ºC and 4 ºC—close to the water density inversion temperature (3.98 ºC)—while the inner enclosure ranged from 63ºC to 4 ºC. The process was simulated using conjugate heat transfer solvers within the OpenFOAM Finite Volume Method framework. Various water density models were analyzed, compared, and validated against experimental data. Models lacking a density inversion point to accurately simulate this process underestimated the time required for the inner enclosure to reach the final temperature (4 ºC)