In: Mechanical Engineering
Blood flows through a ventricular assist device (a pump) at a rate of 100 mL/s. It enters at a pressure of 110 kPa, temperature 36.50°C, and speed 0.25 m/s. It leaves at 125 kPa, temperature 36.52°C, and speed 0.40 m/s. Heat transfer from the blood in the pump is negligible. The outlet is 40 mm above the inlet. (Note: the thermophyhsical properties of blood may be approximated by properties of liquid water at 37°C.) (a) Calculate the rate of work done on the fluid by the pump. [13] (b) Calculate the fraction of pump work converted to enthalpy, kinetic energy, and potential energy. Comment on the relative importance of these effects. [4] (c) What fraction of pump work is used to raise the temperature of the blood? [3] (d) Calculate the minimum power required to pump the blood with the flow rate and pressure rise given here. Why is higher power required in practice? [5]