The mass flow rate of a Freon refrigerant through a heat exchanger is 5 kg/min. The enthalpy of entry Freon is 238 kJ/kg, and the enthalpy of exit Freon is 60.6 kJ/kg. Water coolant is allowed to rise 6 ?C. The water flow rate in kg/min is a. 24 b. 35 c. 83 d. 112
1) find Δh (in) of the system from the freon (h in-h out) 2) multiply by mass flow rate to get ΔH (in) for system 3) find specific heat transfer for water to rise 6 ?C (Δq(out)=mcΔt) 4) assumption: for constant pressure, Δq(out)=Δh(out) 5) first law: ΔH (in) = Δh(out) x mass flow of water, all is known but mass flow rate of water.
