Lecture Objectives Answer your question related to the software Define your final project Compare parameters for Air Quality analyses • Air-change effectiveness • Contaminant removal effectiveness
Final project topics Open for various topics • Research problems • Different environmental engineering problems • Natural ventilation in buildings - validation • Smoke distribution simulation • Unsteady-state flow • Your topic • Various Engineering Problems • Natural ventilation – buoyancy and cross-ventilation • Exhaust and supply air positions in large spaces • Your topic
IAQ parameters Number of ACH quantitative indicator ACH - for total air - for fresh air Ventilation effectiveness qualitative indicator takes into account air distribution in the space Exposure qualitative indicator takes into account air distribution and source position and intensity
IAQ parameters • Age-of-air air-change effectiveness (EV) • Specific Contaminant Concentration contaminant removal effectiveness e
Single valueIAQ indicatorsEv and ε • Contaminant removal effectiveness (e) • concentration at exhaust • average contaminant concentration Contamination level • 2. Air-change efficiency (Ev) • shortest time for replacing the air • average of local values of age of air Air freshness
Depends only on airflow pattern in a room We need to calculate age of air (t) Average time of exchange What is the age of air at the exhaust? Type of flow Perfect mixing Piston (unidirectional) flow Flow with stagnation and short-circuiting flow Air-change efficiency (Ev)
Contaminant removal effectiveness (e) • Depends on: • position of a contaminant source • Airflow in the room • Questions 1) Is the concentration of pollutant in the room with stratified flow larger or smaller that the concentration with perfect mixing? 2) How to find the concentration at exhaust of the room?
Ev= 0.41 e= 0.19 e= 2.20 Differences and similarities of Evande Depending on the source position: - similar or - completely different air quality