A car radiator uses hot engine coolant (stream 1) at 95C to heat cold air (stream 2) entering at 20C. The desired outlet temperature for the air is 70C. The overall heat transfer coefficient (U) for the raidator is 150 W/m²K , and the total heat transfer area (A) is 0.8 m². The mass flow rate of coolant (m1) is twice the mass flow rate of air (m2). Determine the effectiveness of the heat exchanger.