The cardiovascular counter-current heat exchanger mechanism is to warm venous blood from 28°C to 35°C at a mass flow rate of 2 g/s. The artery inflow temperature is 37°C at a mass flow rate of 5 g/s. The average diameter of the vein is 5 cm and the overall heat transfer coefficient is 125 W/m² · K. Determine the overall blood vessel length needed to warm the venous blood to 35°C if the specific heat of both arterial and venous blood is constant and equal to 3475 J/kg · K.