Page 47 - Industrial Ventilation Design Guidebook

I 2 CHAPTER 2 TERMINOLOGY
TABLE 2.1 Ideal Room Air Conditioning Strategies

Strategy

Piston Stratification Zoning Mixing

Description To create unidi- To support flow To control air To provide
rectional air- field created by conditions within uniform
flow field density differ- selected zone in conditions
over the room ences by the room by the throughout;
area by replacing the supply air and the ventilated
supply air airflow out allow stratifica- space
from the room tion of heat and
area with contaminants in
supply air the other room
areas

Heat, humidity, anc
contaminant
distribution*

Main characteristics Room airflow Room airflow Room airflow pat- Room airflow
patterns con- patterns con- terns controlled patterns con-
trolled by trolled mainly partly by supply trolled typi-
low-momen- by buoyancy; and partly by cally by high-
turn unidirec- supply air dis- buoyancy momentum
tional supply tribution with supply air-
airflow, low momen- flow
strong turn
enough to
overcome dis-
turbances
Ideal contaminant
and heat removal
efficiency
Typical application
(example of a
general room air
distribution
method)

3
*x-axis: °C, mg/m , g/kg; y-axis: room dim. (e.g., height); SU = supply, EX = exhaust