A room is air-conditioned with a primary air fan coil system and is maintained at 24C, as shown in Figure Q2. A constant amount of 0.2 m/s primary outdoor air at 15C and 90% saturation air flows to the fan coil inlet to mix with the return air. The fan coil unit delivers airflow of 1 m/s. Assuming that supply air leaves the fan coil to be 90% saturated. Fan heat gain in both PAU and FCU can be ignored. 2-a) At full load condition, the space sensible and latent loads are 10.5 kW and 2 kW, respectively. Determine the supply air temperature, the indoor air relative humidity (RH) and the sensible and latent cooling capacity of the fan coil at the design condition. 2-b) At part load condition, the space sensible load falls is reduced by 50%, and the latent load remains to be 2 kW. The primary air state and flow rate as well as the supply air flow rate of FCU remain unchanged. At this condition, assuming the supply air leaving the FCU to be 80% saturated. Determine the space RH, the sensible and latent cooling capacity of the fan coil at the given part load condition. 2-c) Based on the results obtained in a) and b) as well as the control of the two-way chilled water valve, analyse the major problem with this system operating at part load condition, recommend a better design method of fan-coil unit when operating at part load condition and briefly introduce its working principle. Outdoor air Cooling coil Primary air handling unit Supply air Primary air Room Fan-coil Figure Q2 Primary air fan-coil system Return air grille