Design construction and testing of a heat loop for study of fouling and its interrelationship to corrosion in heat exchanger tubes

A heat loop suitable for the study of thermal fouling and its relationship to corrosion processes was designed, constructed and tested. The design adopted was an improvement over those used by such investigators as Hopkins and the Heat Transfer Research Institute in that very low levels of fouling could be detected accurately, the heat transfer surface could be readily removed for examination and the chemistry of the environment could be carefully monitored and controlled. In addition, an indirect method of electrical heating of the heat transfer surface was employed to eliminate magnetic and electric effects which result when direct resistance heating is employed to a test section. The testing of the loop was done using a 316 stainless steel test section and a suspension of ferric oxide and water in an attempt to duplicate the results obtained by Hopkins. Two types of thermal ·fouling resistance versus time curves were obtained . (i) Asymptotic type fouling curve, similar to the fouling behaviour described by Kern and Seaton and other investigators, was the most frequent type of fouling curve obtained. Thermal fouling occurred at a steadily decreasing rate before reaching a final asymptotic value. (ii) If an asymptotically fouled tube was cooled with rapid cir- ·culation for periods up to eight hours at zero heat flux, and heating restarted, fouling recommenced at a high linear rate. The fouling results obtained were observed to be similar and 1n agreement with the fouling behaviour reported previously by Hopkins and it was possible to duplicate quite closely the previous results . This supports the contention of Hopkins that the fouling results obtained were due to a crevice corrosion process and not an artifact of that heat loop which might have caused electrical and magnetic effects influencing the fouling. The effects of Reynolds number and heat flux on the asymptotic fouling resistance have been determined. A single experiment to study the effect of oxygen concentration has been carried out. The ferric oxide concentration for most of the fouling trials was standardized at 2400 ppM and the range of Reynolds number and heat flux for the study was 11000-29500 and 89-121 KW/M², respectively.

A Grand Tour: A Catalogue of Eighteenth-Century Print Works at Memorial University Libraries

This catalogue highlights forty-seven of the 1,180 eighteenth-century imprints held by Memorial University Libraries. Intended as a general introduction to eighteenth-century literature in its original formats, the work is aimed at students and teachers of book history and bibliography, as well as at the general reader. Consequently, the focus is broad, highlighting the emerging free press, imaginative literature—particularly the novel—travel literature, street literature, illustration, as well as works of religion, philosophy, science, and medicine. The introduction discusses each of the works presented in the catalogue and makes a case for the collection as a whole as representing a range of developments both in eighteenth-century literature and in the book trade. Catalogue entries highlight the physical artifact, offering both description and photographic evidence. Each entry contains information about the author and the content of the work, and attempts to place the work in its literary context.