Specifications
74
where T
c
= temperature in degrees Celsius.
The vapor pressure of the air is also found according to the following equation:
where T
dc
= dew point temperature in degrees Celsius.
Absolute humidity is declared as the mass of water vapor that is contained in per
unit volume of space. The formula is:
where m
w
= mass of water vapor, and V
net
= total moisture of air (in m
3
). Each
measurement variable previously explained all represent the same water vapor in
air condition.
Section 3: Design
3.1 Software Design
The main control unit‟s software design focus is based on simplicity. In order to
meet our requirements, the unit needs to monitor a wire temperature, control
multiple relays to power HVAC units and to control venting systems. In addition
to the automated controls of the system, it must have a user interface for which a
user can adjust system control settings.
The heart of the control system is a use case that handles all of the HVAC
controls. Within this operation we will have our operational conditions checked,
and based on adjustable user settings, this use case will pass information to
power relays or adjust venting systems. In making a decision for which systems
to enable, the control process must first receive readings from a wireless
temperature and relative humidity sensor. With this current information, the
system reads the settings that the user adjusted to suit their own comfort and
power levels. Figure 32 shown below is the use case diagram for the main
control unit.