Numerical and Experimental Study of an Air Extraction System

A numerical and experimental analysis is performed on the case of an air extraction system for a relatively large kitchen, equipped with a reintroduction system blowing untreated air directly under the hood. Such an approach, while leading to a notable energetic saving, concedes a decrease of the suction efficiency, since the extraction system is partially utilized to convey the clean air coming from the outside. At the same time, the presence of a jet, below the hood ceiling, directed towards the extraction filters, may or may not have a beneficial effect on the operators comfort. A 2D numerical model of a central section of the hood is built, considering isothermal conditions. Numerical results are validated against the outcomes of an in vivo measurement campaign, carried out on an existing installation. The obtained model is then used to perform a preliminary parametric study, in order to determine the influence of the ratio between inlet and outlet flow rates on the local flow field, and, ultimately, on the system effectiveness.