ALLAN PHILIP COLBURN-THE YEARS WITH DU PONT

IT WAS a fortunate circumstance that brought Allan Colburn to the Du Pont Experimental Station, 23 September 1929. A research group in chemical engineering had just been organized, under the far-sighted administration of C. M. A. Stine, Chemical Director, and A. P. Tanberg, Director of the Experimental Station, paralleling and extending the groups set up to undertake fundamental research, not tied to immediate commercial objectives, in polymer chemistry, headed by W. H. Carothers, in colloid chemistry, and in catalysis. The chemical engineering group, which I had the privilege of heading, was built around the nucleus of men who had been working on improvements in the manufacture of acids, but Colburn was one of the very first additions made to prosecute the fundamental research objectives. He had conducted at the University of Wisconsin, with 0. A. Hougen, a noteworthy investigation in the field of heat transfer [19]. It was this, indeed, which brought him to the attention of the Du Pont Company, and it was natural, therefore, that heat transfer was the topic assigned to him for study. The objectives of the research group in chemical engineering were to find out what was known about the several unit operations, with the aim of making information available to the people engaged in the design of plants that would lead to the specification of equipment and methods of operation that would be the most economical and give the greatest assurance of satisfactory performance. Colburn fell in readily with these objectives. He attacked his assignments with unfeigned zeal, and found, I feel sure, real satisfaction in carrying them out. The chemical engineering research group, with a unified central aim but with the members each responsible for separate topics, provided a congenial atmosphere, refreshed and stimulated by the frequent visits of W. H. McAdams as a consultant. Colburn’s first publication from the Experimental Station was in a sense an extension of his Wisconsin thesis [q. His work there was directed towards improving the design of dehumidifying gas coolers used in the manufacture of city gas. It is cited here as establishing the early date of his putting forward of the “Colburn analogy”, as it might better be called, even though not in the exact form in which it has come to be known. In this paper Colburn extended the idea he lirst developed in the second part of his earlier publication [18] ; namely, that the incorporation of the ratio of the molecular diffusivity to the momentum diffusivity (kinematic viscosity) should accomplish for mass transfer in conduits what the Prandtl and Taylor modifications of the Reynolds analogy did for heat transfer, with the function of the Prandtl number called for to conform to the velocity distribution in turbulent flow. Colburn was able to show that the corresponding expression did show agreement with the Wisconsin data on dehumidification, as well as with data obtained some years before at the Experimental Station by C. H. Greenewalt on the drying of air with sulfuric acid in a falling film column. The group of three papers published in 1931 exemplifies Colburn’s special talents [2, 7, 201. The chemical engineering group was, among other things, looking into the possibility of designing an integral converter-heat exchanger for the catalytic conversion of SO2 to SOs, and Colburn undertook to carry out tests to determine the heat-transfer coefficients we could