This Special Issue addresses topics on the water–energy–food (WEF) nexus along with other water-related topics, such as water resources, irrigation and drinking water supply systems, hydraulics and pollution. Several threats jeopardize freshwater availability and quality, energy and food availability. Integrated management approaches are absolutely necessary for pursuing sustainability. This Special Issue addresses various subjects and includes 29 peer-reviewed papers that have been grouped into the following categories: the WEF nexus, water resources and irrigation systems, drinking water supply systems, hydraulics and pollution. Some of them were selected from the Third Efficient Water Systems (EWaS) International Conference, entitled “Insights on the Water–Energy–Food Nexus,” after a thorough content update. Summaries of the papers are briefly presented in this Editorial.

This work aims at simulating a retort sterilization process of flexible packaging, performed in autoclave. ANSYS CFD© software has been used in this study to simulate the heat transfer inside the retort chamber. Flexible packaging filled with a pumpkin soup has been modelled. Three-dimensional (3D) geometrical configuration of the equipment has been designed and then simulated to evaluate the sterilization level achieved by each packaging inside the retort chamber. In particular, the internal temperature of the product situated in the cold spot of the chamber has been monitored during 5 min of the process (after reaching 85°C inside the product) in order to monitor the time/temperature trend. Experimental tests have been finally performed to validate the simulation model of heat exchange. The sterilization process takes place in a retort chamber by means of “overheated water sprayed” at 403 K and a pressure of 5 atm. Results show a good agreement between the simulated results and the real retort process and confirm the potential value of the simulation model to evaluate the process performance.

This paper reports on the development of an approximate empirical-CFD modelling procedure combining experimental correlations for the heat and mass transfer coefficient determination and specific user-defined functions (UDF) implemented in the commercial CFD code Fluent to simulate the interrelationships at play between airflow and transfers of unwrapped food products bathing in air. Transfer modelling required specific calculation to account for water evaporation from the product surface. Mean transfer coefficients at the air-product interface were determined empirically from validated experimental correlations, where the CFD mean air velocity that is calculated in a small user-defined volume surrounding the product was incorporated. Internal water diffusion was taken into account by considering the product as a motionless fluid composed of dry matter and water. The procedure developed allows, in a single CFD calculation using a single mesh, temperature and water concentration fields to be computed and the water loss kinetics of the products to be determined together with the temperature and relative humidity fields of the air flowing around them. Although the established procedure was set up with the aim of assessing heat and water exchanges occurring in large stacks of unwrapped food products subjected to airflow, this last was validated for modelling, first, one-dimensional drying of a meat cylinder and second, three-dimensional drying of five cylindrical plaster casts placed in a row. Its application to the ripening of a row of six cheeses is also discussed.