Rationale :
Buildings operations account for 40% of the total US energy consumption. This corresponds to about $170 Bn worth of cash. One third of this energy is wasted due to inefficiency in buildings controllers. The average household spends about $2000 a year on energy bills, over half of which goes to heating and cooling. To test new building technologies and to bridge the gap between computer simulation and modeling and the full scale buildings, a small scaled HVAC rig was built. This project is carried out to set baseline PID controllers for the HVAC components as well as designing and implementing a wireless sensor actuator network that facilitates two way communications between computer and the rig. This project also simplifies interaction with the rig and acquiring data by implementing a GUI in Matlab, a well-established statistical software package.
In order to control the existing HVAC rig, one needs to understand the basic operation of the HVAC. The scaled HVAC rig consists of two main loops; the chiller water loop and the condenser loop. Peltier module has been used to remove heat from the chilled loop and convey it to the condenser loop where heat is removed by passing through a forced air heat exchanger in the condenser loop as shown in figure (1). The chiller water loop consists of a water block attached to the cold side of the Peltier Module. The water flowing through the water block acts as a heat source at the side of the thermoelectric module. The chilled water CHW supplied from the water block goes through a cooling coil available in the conditioned space. This CHW picks up heat in the conditioned space by having a fan blowing air through the cooling coil. The hot water returning from the cooling coil is pumped by a circulating pump to go through the water block (chiller) and this process repeats itself.
The condenser loop consists of water block attached to the hot side of the Peltier module. Water flowing through the water block acts as a heat sink at the hot side of the thermoelectric module. Heat is being removed from the condenser side of the Peltier and being pumped through a double heat exchanger that cools it down using fans. The more heat removed from this loop the better the Peltier performs, the more we can cool down the chilled water loop