A dual-duct multi-zone air conditioning system, consisting of a heating coil and a cooling coil, supplies air to 3 identical zones, maintained at 24°C db-temperature and 17°C wb-temperature. For each...

A dual-duct multi-zone air conditioning system, consisting of a heating coil and a cooling coil, supplies air to 3 identical zones, maintained at 24°C db-temperature and 17°C wb-temperature. For each zone the sensible and latent heat loads are 34 kW and 22 kW respectively. Of the total return air mass flow from the zones, 25% is discharged and replaced with outdoor air at 35°C db-temperature and 40% relative humidity. The air leaving the heating coil is at 40°C dbtemperature. At the exit of the cooling coil the air is at 10°C dbtemperature and 90% relative humidity. The pressure is constant at 101.3 kPa. (a) Draw a schematic diagram of the system. (b) Determine (i) the mass flow rate of air through the heating coil, (ii) the heat input by the heating coil, (iii) the mass flow rate of air through the cooling coil, and (iv) the refrigeration capacity of the cooling coil. Check the overall energy balance for the system.