Consider an IDEAL vapor-compression air conditioner with a cooling capacity of Q dot_c= 4 tons whose evaporator is used to cool dry air in an air handler duct from T_a,in= 75 degrees F down to T_a,out= 62 degrees F. The refrigeration cycle uses R-134a. The evaporator operates at a pressure of 60 psia, and refrigerant exits the evaporator as saturated vapor. The condenser operates at a pressure of 200 psia, and refrigerant exits the condenser as saturated liquid. 1 Ton= 12000 Btu/hr
Find:
a) compressor work per unit mass, w_c, in Btu/lbm
b) the heat transfer from the evaporator per unit mass, q_c, in Btu/lbm
c) cycle COP
d) refrigerant mass flow rate, m dot_r, in lbm/hr
e) the mass flow rate of the air through the handler, m dot_a, in lbm/hr
f) the electric power consumed by the compressor assuming a 100% efficient electric compressor motor
a) w_c= 10.7 Btu/lbm
b)q_c= 55.8 Btu/lbm
c) COP= 5.21
d) m dot_r= 884 lbm/hr
e) m dot_a= 15400 lbm/hr
f) motor power= 2.78 kW