Measurement of Heat Transfer Coefficients for Axial Air Flow through Eccentric Annulus and Seven-Rod Cluster

抄録

The heat transfer characteristics of non-concentric annuli with various eccentricities and also of a seven-rod cluster were experimentally determined by means of mass transfer technique. A coating of naphthalene was applied to the surface of the test rod and changes in its thickness measured. The mass transfer coefficients have been represented in terms of Colburn's j-factor, with which both the average and local values were analyzed. The measured average heat trans-fer j-factors were found to be in part equal to those for smooth round ducts, but the circumfer-ential variations of the local factors for the eccentric annulus did not agree with the theoretical prediction proposed by Dwyer & Yu. The existence of secondary flow in the seven-rod cluster is also discussed.