In the air conditioning system, shown schematically in Fig. P12.10.1, chilled water is pumped to two cooling coils A and B with cooling capacities of 45 kW and 60 kW respectively. The temperature rise...

In the air conditioning system, shown schematically in Fig. P12.10.1, chilled water is pumped to two cooling coils A and B with cooling capacities of 45 kW and 60 kW respectively. The temperature rise of water in each coil is 5°C. The flow circuit from 2 to1 through the pump includes 10 m of piping, two globe valves, and the evaporator with a head loss of 4 m. The flow circuit from 1 to 2 through coil A has 5.1 m of piping, a gate valve, and the cooling coil with a head loss of 1.7 m. The flow circuit from 1 to 2 through coil B has 1.5 m of piping, a gate valve, and the cooling coil with a head loss of 2 m. Based on the chilled water flow rates through the three flow circuits the following pipe diameters have been selected (see Fig. P12.10.1): D1 = 65 mm, D2 = 52.5 mm, D3 = 48 mm. (i) Calculate the required water flow rate through the evaporator. (ii) Check whether the selected pipe diameters satisfy the guidelines listed in section 12.6.2. (iii) Calculate the required rise of total head across the pump. (iv) If the efficiency of the pump is 70%, calculate the power input