An air handler is a large unmixed heat exchanger used for comfort control in large buildin...

An air handler is a large unmixed heat exchanger used for comfort control in large buildings. In one such application, chilled water (cp = 4.2 kJ/kg•K) enters an air handler at 5oC and leaves at 12oC with a flow rate of 1000 kg/h. This cold water cools 5000 kg/h of air (cp = 1.0 kJ/kg•K) which enters the air handler at 25oC. If these streams are in counter-flow and the water stream conditions remain fixed, the minimum temperature at the air outlet is

(a) 5oC 

(b) 12oC 

(c) 19oC 

(d) 22°C 

(e) 25oC