Entropy Generation Rate for a Peristaltic Pump

In view of the second law of thermodynamics, the idealized process is usually so selected as to be one of minimum available energy degradation. A measure of departure from this ideal process is the entropy generation rate. In this paper, we shall investigate this aspect concerning an adiabatic peristaltic pump. Our analysis also exhibits the general features of a flow in a contracting tube. It is shown that the dynamics of the system can be reduced to that of a classical Hagen-Poiseuille flow with a source term in the continuity equation and an additional induced force in the momentum equation. In reference to exergy, the analysis reveals that peristaltic pumps generate more entropy than steady walled tubes and are not, from this point of view, competitive devices. The reason for this high-energy degradation is found in the dynamic behavior. The flow rate is not constant along the tube, but increases as sections downstream are reached. This results in high velocity gradients and therefore in strong dynamic irreversibility, which is the prime entropy source of the system. For the classical Hagen-Poiseuille flow, the entropy is mainly generated by heat diffusion.