An open plan office is to be air-conditioned in summer to maintain comfort conditions.
The room has a sensible heat gain from lighting of 4.5 kW, equipment 3.0 kW and 30
people. The sensible emissions per person are 90 W and the latent gains are 50 W.
Equipment within the space emits 1.0 kW of latent heat.
The building design temperature is 22°C db and 50% RH when the external design
conditions are 30°C db and 21°C wb. The design fresh air requirement for the building
is 15% of the total flowrate. Assume the air supply temperature is 15 °C.
(a)
(i) Draw a sketch showing a schematic of the air-conditioning system.
(ii) Provide a sketch of the psychrometric process.
Determine the following:
(b)
The temperature and relative humidity of the mixed air.
(c) Mass and volume flow rate of air entering the room.
(d)
The change in moisture content of the air as it passes over the cooling coil
(e) The load on the heater battery.
(f)
The load on the cooling coil.
(g)
Draw a schematic arrangement for the plant indicating mass flow rates,
volume flow rates, air temperatures and relative humidities in each part of the
system.
