Modelling of air exchange "air supply from above - removal from above"

The efficiency of the air exchange scheme "air supply from above - removal from above" is considered. Heat and mass exchange of the system including: mathematical model of a human being (breathing process with release of carbon dioxide, heat and water vapour into the environment) with simultaneous heat release from the clothed body surface; supply ventilation system (CO2, water vapour and heat input with atmospheric air); exhaust ventilation system (removal of the above mentioned harmful substances contained in the air). Application of numerical modelling ANSYS CFD (Computational Fluid Dynamics) based on continuity equations and averaged Reynolds-Averaged Navier-Stokes equations "RANS" (Reynolds-Averaged Navier-Stokes) gave the following results: the inverse problem of ventilation was solved - for the initially polluted investigated space of the room the interaction of systems (human and operating supply and exhaust ventilation unit) was considered; monitoring and visualisation of changes in CO2 concentration, temperature and relative humidity in the investigated space by time and by height of the room; the obtained results are compared with the previously obtained results of changes in carbon dioxide concentration, temperature and relative humidity in the ventilated space under the air exchange scheme "air supply from above - removal from below" (Scheme A) and normative documents. The dynamics of excess heat, humidity and carbon dioxide (CO2) assimilation allowed us to assess the efficiency of ventilation systems and predict an increase in their energy efficiency when bringing air parameters up to standard values. Changes in the air environment are typical for premises with mechanical supply and exhaust ventilation (flow classrooms of educational institutions, classrooms of schools, group rooms of kindergartens, conference halls, offices). For this type of premises the main air pollutants are carbon dioxide, water vapour and heat.