B. AIR CONDITIONING SYSTEM ANALYSIS Heating coils Expansion Valve T = 20C -leeeeene T 15C -100% Condenser Compressor Refrigerator Working Fluid (R134a) Evaporator 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Condensate T-38C Tub,126 C P-101.325 kPa m = 0.5kg/s 15C Condensate Water Heating Section Cooling Section Figure 3. Air conditioning process and refrigeration cycle Figure 3 shows an ideal refrigeration cycle using R134-a as the working fluid and operates between 0.6 MPa and 1.6 MPa. The refrigeration cycle is used to cool an air flow in the cooling section of an air conditioning process. The air enters the cooling section at rate of 0.5 kg/s and 1 atm pressure. Measured dry bulb temperature and web bulb temperature is 38 C and 26 C, respectively. The air cooled until condensed at 15 C. The condensed water flows out from this section. Then, the air is heated in the heating section until it reaches 20 C. Determine: i) the condensed water flow rate (kg/s), ii) the rate of heat rejection from the cooling section (kW), iii) the exit relative humidity and heating capacity in the heating section if the exit temperature is 20C, and iv) the refrigerant mass flow rate (kg/s) and heat rejection to the environment from refrigeration cycle (kW) Exit air from heating section O....... Examination Hall .............. Fresh air Figure 4. Adiabatic mixing process with a fresh air The examination hall needs to meet a human comfort requirement. It can be achieved by adding fresh air at the exit of the heating section, using adiabatic mixing airstream chamber. If the mass flow rate of the fresh air is 0.25 kg/s, calculate the range of temperature and relative humidity, of the fresh air to achieve human comfort level in the examination hall.