Water flows counter-currently through two concentric pipes with inner pipe of 1 OD and outer pipe of 2OD. Ignore the thickness of inner pipe for calculation purpose. Cold water enters inner pipe at 1m/s at 300C and exits at 600C. Hot water enters outer pipe at 900C at a velocity of 0.5 m/s. Compute LMTD. Cp=4180 J/kg K, = 990kg/m3