Take Home Exam

Q1: The following data refer to public hall AC system:

100% Outdoor conditions: tab= ?; o = ?

Comfort conditions: tab = 20°C; = 50%

Seating capacity of the hall = z

Outdoor air supplied = 0.3 m³/min/person

If the required comfort condition is achieved first by adiabatic humidification and

then sensible cooling process find:

1. The capacity of the cooling coil in (TR)

2. The coil surface temperature if the by-pass factor is 0.25

3. The mass of water required in the humidifier, in kg/hr

4. The efficiency of the humidifier

Q2: Air enters a cooling coil (of By-Pass factor BF) at 24°C dry-bulb-temperature

and 50% relative humidity with a dry air mass flow rate of 0.9 kg/s. The air leaving

the cooling coil at 9°C is reheated to 13°C. The total pressure is constant at P kPa.

Determine

(i) the Apparatus dew-point temperature (ADP)of the coil,

(ii) the rate of moisture removal in the cooling coil, in kg/hr

(iii)

the refrigeration capacity of the cooling coil, in kW

(iv)

The heat input rate of the heating coil, in kW

Enthalpy

kikg