Abstract: Forced convective heat transfer under steady flow in a helical recuperator is being studied, employing similanity principles. Water, glycerin-water solution and air are used separately as medium for heat transfer, and Convective heat-transfer coefficients are determined over a rather wide range of Dean number and Prandtl number. The correlations among Nusselt number, Dean number and Prandtl number are found by the least squares method: Nu = 1.2Dn0.53Pr0.29; Dn = 2250-16500, Pr=2.5-8.5 Nu = 0.23Dn0.64Pr1/3; Dn = 2900-9000, Pr=0.7 At the same time, the modified graphical method of wilson is used to determine the individual convective heat-transfer coefficients in the recuperator, and it is found results that they agree satisfactorily with experimental.