1. Objectives Finish with Multizone Systems
Review/Learn about HVAC Configurations
Learn about cooling towers

2. Multizone
Systems 2

3. 3

4. 4

5. Single zone CAV

6. Single zone multi-room CAV

7. Multi zone CAV with Reheater

8. Duct reheat unit

9. Multizone CAV Dual Duct System

10. Dual duct terminal (Mixing box)

11. Single zone VAV

12. Multi zone VAV

13. VAV box

14. Multi zone VAV with Reheater

15. CAV Dedicated Outdoor Air System (DOAS) with Fan Coil Units
Exhaust
100%OA
For ventilation
and humidity
control
Fan coil units for
heating and cooling

16. Fan Coil Units
Fan coil Units can be combined with mechanical ventilation or rely on infiltration

17. VAV Dedicated Outdoor Air System (DOAS) with occupancy sensors
Exhaust
100%OA
VAV box
VAV box
CO2
CO2
For ventilation
and humidity
control
Fan coil units for
heating and cooling

18. Fan Terminal Units Same as fan coil
Can be with
or without
recirculation

19. HVAC Systems Single zone Multi zone All Hydroinic that relay on
infiltration
VAV
CAV
CAV
VAV
With and
without
humidity
control
With and
without
reheaters
Dual
duct
Dual
duct
With
reheaters
DOAS with
fan coils
DOAS with
fan coils
This is not the complete list !

20. Cooling towes Similarity and difference between
Evaporative coolers and
Cooing towers

21. Cooling Tower
Similar to an evaporative cooler, but the purpose is often to cool water
Widely used for heat rejection in HVAC systems
Also used to reject industrial process heat

22. Air Washer Sprays liquid water into air stream
Typically, air leaves system at lower temperature and higher humidity than it enters

23. Schematic

25. Cooling Tower

27. Solution Can get from Stevens diagram (page 272)
Can also be used to determine
Minimum water temperature
Volume of tower required

28. Real World Concerns We need to know mass transfer coefficients
They are not typically known for a specific direct-contact device
Vary widely depending on packing material, tower design, mass flow rates of water and air, etc.
In reality, experiments are typically done for a particular application

29. Summary
Heat rejection is often accomplished with devices that have direct contact between air and water
Evaporative cooling
Can construct analysis of these devices
Requires parameters which need to be measured for a specific system