A refrigeration unit operates on the ideal vapor compression refrigeration cycle and uses refrigerant-22 as the working fluid. The operating conditions for this unit are evaporator saturation temperature of 25oC and the condenser saturation temperature of 45oC. Selected data for refrigerant-22 are provided in the table below.

For R-22 at P = 1728 kPa and s = 0.9344 kJ/kg·K, T = 68.15oC and h = 283.7 kJ/kg. Also, take cp,air = 1.005 kJ/kg·K.
(a) Sketch the hardware and the T-s diagram for this heat pump application.
(b) Determine the COP for this refrigeration unit.
(c) The evaporator of this unit is located inside the air handler of the building. The air flowing through the air handler enters the air handler at 27oC and is limited to a 20oC temperature drop. Determine the ratio of volume flow rate of air entering the air handler (m3air/min) to mass flow rate of R-22 (kgR-22/s) through the air handler, in (m3air/min)/(kgR-22/s). Assume the air pressure is 100 kPa.

Transcribed Image Text:

T, C Psat, kPa hh kJ/kg h kJ/kg S /kg.K 5 421.2 38.76 248.1 0.9344 45 1728 101 261.9 0.8682