PURPOSE: To enhance the heat transfer rate of particles of a heat accumulating material by a method wherein a flow of a fluid entering a heat-accumulating layer is preliminarily disturbed sufficiently by placing a vortex flow generating member on the upstream side of the heat-accumulating layer, in a regenerative heat exchanger used for a regenerator in a Starling engine or the like.

CONSTITUTION: The flow of a working fluid entering as a laminar flow is disturbed when the fluid passes through the vortex flow generating member 11 such a metallic net, and the sufficiently disturbed flow thus formed collides against the first row of spherical particles 5... in the heat-accumulating tank 6. As a result, even at the first row of the particles 5..., a high heat transfer rate comparable to those at the second and later rows of the particles can be obtained. Accordingly, the heat-exchanging efficiency of the heat exchanger as a whole can be greatly enhanced.