Experimental investigations of mean mass/heat transfer coefficients at the surface of two different curved short ducts of rotors of the sucking and Forcing regenerative heat exchanger were made for forced laminar flow in static conditions. An electrolytic technique was employed. The results For two types of ducts are presented finally by correlations for j(M) Chilton-Colburn coefficient vs Reynolds number. The results for one of the ducts are consistent with the previous results of the author for the inner surface and developed flow in a straight annular duct with similar L/D-h.