b.
An air-conditioning system takes in air at a volumetric flow rate of
230 m³/min, 101.325 kPa, 30 °C and 70% relative humidity and delivers it
at 22 °C and 50% relative humidity. The air flows over the cooling coils,
where it is cooled and dehumidified, and then over the resistance heating
wires where it is heated to the desired deliver temperature. Then the
refrigeration system operates at steady state condition with refrigerant
R410a is used as a working fluid. Saturated vapour of R410a enters the
compressor at -10°C and leaves the condenser as saturated liquid at 26
bar. Sketch the process using psychrometric chart. Evaluate
i.
the mass flow rate of the dry air [kg/min],
ii.
the rate of moisture removed from the air [kg/min],
iii.
the required cooling capacity capacity [kW],
iv.
the mass flow rate of the refrigeration system [kg/s],
v.
the power of compressor [kW].
For air, take R = 0.2871 kJ/kg.K and $c_p$ = 1.005 kJ/kg.°C, and for water
vapour, take R = 0.4619 kJ/kg.K.
