The mullions have a double tube structure vertically attached to the window frame by an aluminum fin. The outer tube is aluminum. The inner tube is steel. The space between these two tubes is filled with epoxy resin. The detailed window frame and mullion structures are shown in Figure 5.
There are 26 groups of mullions in the IW. Each group has four mullions controlled by one control valve. The surface temperature of the mullions is controlled based on the outside and inside temperatures and the room air set point temperature.
Figure 5. Detailed Window Frame and Mullion Structures
The overhead radiant panels are free-hanging ceiling radiant panels without topside insulation. The panels consist of several panel modules. The two pieces of the panels are connected together by a U-shaped tube to form one module. A cross section of the copper tube and aluminum panel is shown in Figure 6.
Figure 6. Detailed Panel Structure