1. Announcements Exam 1 Next Class (Thursday, March 14th):
Max 90 minutes!
We will start at 10:55 am.
Open book Open notes
Comprehensive

2. Objective VAV vs CAV and overall HVAC system Finish with HW3
Review the class material for exam

3. Multizone constant air volume with reheat
55°F
62°F
Require less
cooling

4. Multizone VAV
55°F
Vary the flow

5. Building HVAC - Delivery Systems
Heating and cooling energy production
Transport - refrigerant
- water
- ….
Cooling plant
Energy storage plant
Heating plant
Building HVAC - Delivery Systems
All air system
(can use water or
refrigerant
in cooling coil)
All water system
(for heating you can use
steam instead water)
Combined system
DOAS
VAV
With
reheater
CAV
With
Zonal
terminal
units
Multi zone
air
system
- Ventilation
- Building
latent load
Single zone
(a whole apartment
can be the single zone)
Multi zone
water
system
-Building
sensible load
Fan
Coil
Baseboard
heater
Radiant
panels
Dual
duct
VAV
ceiling
floor
CAV-VT
VAV

6. Homework Assignment 3
Table 1 Results of cooling load calculation and required amount of fresh air for ventilation
Zone 1
Zone 2
Zone 3
Whole building
Sensible cooling load for zone
Time when the max cooling load appear
41000 Btu/h
at 4 PM
45000 Btu/h
at 6 PM
27000 Btu/h
at 8 AM
92000 Btu/h
Sensible cooling load for critical hour for whole building (6 PM)
37000 Btu/h
9000 Btu/h
Latent cooling load (internal sources + infiltration)
5400 Btu/h
5200 Btu/h
16000 Btu/h
Required amount of fresh air based on number of occupants
240 CFM
(12 occupants)
520 CFM
(26 occupants)
1000 CFM
(50 occupants)

7. Review What is purpose of psychrometric chart?
What quantities are on axes?
Diagonal lines?
Curved lines?
What is significant about the saturation curve?
How do you find the dew point temperature?
How to find the enthalpy?

8. Psychrometric Processes
What does sensible heating or cooling look like on the chart?
What does sensible mean? What does latent mean?
Why does some cooling cause dehumidification?
What does an evaporative cooling process look like on the chart?
When two air streams mix, how do you find the conditions for the new air stream?

9. Heat Transfer What defines a heat transfer though the wall?
What are air films and when do you include them in calculations?
What parameters do you need to know for determining the R-value of an airspace?
When do you use R-values and when do you use U-values?

10. Heating and Cooling Loads
What are the major components of a heating load?
What is the difference for a cooling load calculation?
How do you account for heating and cooling loads associated with windows?
With infiltration?
Why are internal gains and solar gains most relevant for cooling loads?

11. Heating systems What is difference between furnace and boiler?
What are advantages of water as a heat transfer fluid?
Where do you get the input data?
Name fuels that can be used in a boiler?

12. Cooling Systems Basics components Process in T-S diagram
What happens to water vapor in an evaporator?
Does an evaporator have a sensible and a latent capacity?
Does a condenser?

13. Ventilation Systems What are the components of AHU?
Which are the major ventilation systems?
Show Air-Conditioning in psychrometric chart.
When to use combination of air and water systems.

14. Integrate Everything in Psychrometric Chart