Q4. PRESSURE, MPa (;) natrijal effect 423-765 () MEBS7012: Air Conditioning and Refrigeration 4. A household split-type air conditioner that uses R-410A as refrigerant adopts the inverter technology for variable refrigerant flow. It has the capability of providing cooling and heating modes by reversing the refrigerant flow using a 4-way valve. (a) Sketch a diagram to show how the 4-way valve can reverse the refrigerant flow to make the indoor unit become a evaporator or a condenser in cooling and heating (4 marks) modes respectively. (b) During a hot summer day, the air-conditioner operates at 40 C condensing temperature and 10 C evaporating temperature. The system is found to operate with some superheating and sub-cooling as the vapour and liquid refrigerant pipes are tied together inside the same insulation. It is found that the sub-cooling is 2 C and the superheating is 3 C. Determine (i) 167*394 watch-447-42? The refrigeration effect (kl/kg) by plotting the refrigeration cycle on the R-410A P-h diagram. (The P-h diagram is to be submitted) (ii) The cooling capacity of the air conditioner if the power input to the compressor is 1.5 kW (-2 hp). x=2kw 4 iny:0.74kw (xfectual pres Ikw=1.34. (-4) (1) The coefficient of performance (COP) of the cooling system. R-410A (8 marks) 50 100 150 200 250 300 350 400 450 500 550 600 650 20 20 10 Reference state: R-38/125 (50/501 200.0 klkg, -1.00 K B for saturated Four C 6 4 2 1 0.8 0.6 0.4 0.2 0.1 0.08 0.06 0.04 0.02 0.01 50 100 Properties compuned with NIST REFPROP V7.C 8 -60 1000 (800 700 800 500 30 50 40; 400 p300 kg/m 200 10 150 8 6 100 60 2 30 20. 1 15 0.8 0.6 10 8.0 0.4 6.0 88888888888 4.0 0.2 3.0 -50 150 200 250 300 265- 350 400 450 500 +27 447 ENTHALPY, kJ/kg Fig. 17 Pressure-Enthalpy Diagram for Refrigerant 410A 550 600 2.0 0.1 1.5 0.08 0.06 1.0 0.80 0.04 0.60 0.40 0.02 0.30 0.01 650 Based on formulation of Lemmon and Jacobsen (2004)