buildings Article Enhancing Heat Treatment Efficacy for Insect Pest Control: A Case Study of a CFD Application to Improve the Design and Structure of a Flour Mill Francesca Valenti ID , Simona Maria Carmela Porto * ID , Nicoletta Tomasello and Claudia Arcidiacono Department of Agriculture, Food and Environment, University of Catania, Via S. Sofia 100, 95123 Catania, Italy; fvalenti@unict.it (F.V.); nicolettatomasello@unict.it (N.T.); carcidi@unict.it (C.A.) * Correspondence: siporto@unict.it; Tel.: +39-095-7147-578 or +39-392-3031-968 Received: 22 February 2018; Accepted: 22 March 2018; Published: 24 March 2018   Abstract: Heat treatment of the indoor environment of flour mills is an alternative technique to chemical fumigation for controlling insect pests. The aim of this research was to assess temperature distribution inside a flour mill during a heat treatment for insect pest control by computational fluid dynamics (CFD) modelling and simulation. The model was validated by using the average values of experimental data acquired during a heat treatment carried out in a flour mill, which is representative of the building materials and techniques used in the milling industry of South Italy. Simulations were carried out in steady-state conditions, and simulated data were validated by the average values of air and wall temperature measurements. Since the modelled temperature distribution in the mill fit the real one with a good accuracy (maximum error equal to 2.57 ◦ C), the CFD model was considered reliable to simulate other operating conditions. Since it was observed that the internal surface temperatures of the mill were much lower than the value required for the success of the heat treatment, equal to 45 ◦ C, the CFD model could be used for improving the effectiveness of heat treatments in the flour mill. Application of the proposed CFD model in the simulation of specific interventions could be aimed at improving both building performance and fan heaters’ localisation, in order to find the best configuration. Keywords: computational fluid dynamics; thermal behaviour; milling industry; heat flux 1. Introduction Milling is the operation of grinding cereals to produce semolina or flour, which are then used in the food industry for the production of bread, pasta, and other derivatives. One of the most important concerns in the milling phase is the proliferation of rodents and insect pests at different life stages, from eggs and larva until the adult form, within the processing environment [1]. This is due to the huge amounts of products treated in the mill that represents the ideal habitat for the proliferation of these pests, with negative consequences on hygiene and quality of the final products. Pest control can be achieved by using different approaches, ranging from the use of chemical protectants, such as gaseous fumigants, to physical treatments [2]. Chemical fumigations with methyl bromide combined with other kinds of approved aerosol insecticides were widely used in the recent past because of the efficient level of disinfestation. However, in 1987, after the Montreal Protocol prohibited the use of substances considered harmful for the ozone layer, methyl bromide was phased out and banned permanently by 2005 [3]. In addition, another condition that has manifested during the recent years and pushed towards the abandonment of chemical methods for pest control regarded the increased resistance of pests to insecticides and gaseous fumigants [4]. Buildings 2018, 8, 48; doi:10.3390/buildings8040048 www.mdpi.com/journal/buildings