Lecture Objectives. Ventilation Effectiveness Thermal Comfort Meshing . IAQ parameters. Age-of-air air-change effectiveness (E V ) Specific Contaminant Concentration contaminant removal effectiveness e. Single value IAQ indicators E v and ε. Contaminant removal effectiveness ( e )
air-change effectiveness (EV)
contaminant removal effectiveness e
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
Piston (unidirectional) flow
Flow with stagnation and short-circuiting flow
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?
Depending on the
- similar or
- completely different
Temperature and relative humidity
Can create draft
Draft is related to air temperature,
air velocity, and turbulence intensity.
Warm ceiling (----)
Cool wall (---)
Cool ceiling (--)
Warm wall (-)
Further Details: ANSI/ASHRAE standard 55, ISO standard 7730
Pat a) Numerical diffusion
The purpose of this project part is to analyze how mesh size and orientation affects
the accuracy of result.
Body-fitted coordinate hexa
Unstructured hexa (2-D)
boundary-fitted, structured grid