<p>Oscillating flow is typically observed in pulse tube refrigerators and exhibits significant differences from unidirectional steady flow. This study investigates the heat transfer characteristics of oscillating flow within the heat exchangers of pulse tube refrigerators, contrasting it with unidirectional steady flow. The influences of non-dimensional parameters, including maximum Reynolds number, Valensi number, pressure ratio, and length-diameter aspect ratio, on the performance of the heat exchangers are thoroughly examined. Consequently, a coupled parameter index for oscillating flow heat transfer was introduced to assess the significance of the oscillating flow's impact. The findings culminated in the identification of a pivotal threshold value of 40.56. This threshold delineates the boundary where a coupled parameter index exceeding this value indicates that the influence of oscillating flow on heat transfer can be disregarded, thereby rendering the oscillating flow analogous to steady flow in terms of heat transfer characteristics.</p>