Numerical investigation of oscillating conjugate heat transfer in pulse tubes

This paper is aimed to investigate the influence of axial heat conduction on conjugate heat transfer for oscillating flow at the pulse tube section of Pulse Tube Cryocoolers (PTCs) via a numerical approach. Finite volume technique with collocated arrangement of grids has been employed to discretize momentum and energy equations. The well-established SIMPLE algorithm was followed for handling the pressure-velocity coupling. The set of individual algebraic equations was solved by the Strongly Implicit Procedure (SIP). Strouhal number (St), wall thickness and solid to fluid conductivity ratio (ksf) are three important parameters which affect the conjugate heat transfer in oscillating flow in pulse tubes. It is shown that the overall Nusselt number (Nu) increases from 5.97 to 28.45 by increasing St from 0.02 to 1. In addition, by increasing ksf from 0.5 to 15, Nu decreases almost 27%, however, for ksf > 15, increasing the solid to fluid conductivity ratio has no influence on the Nusselt number. Furthermore, the cycle averaged friction coefficient at fully developed region increases almost 73% at St = 1 in comparison to St = 0.02.