A solar assisted air conditioning system, 1 kg/sec of ambient air is to be preheated by the same amount of air leaving the system. A counter-flow heat exchanger having an area of 60 m2 with overall heat transfer coefficient of 25 W/m2k is used for this purpose. Assuming Cp for air is 1 kJ/kgK. The effectiveness of the heat exchanger is
1
0.4
2
0.6
3
1.6
4
25