Correlation and Utilization of New Data on Flow Resistance and Heat Transfer for Cross Flow of Gases Over Tube Banks

Abstract

In spite of the commercial importance of the tube bank in heat-transfer equipment, few experimental data previously have been available on convection heat transfer and resistance to flow of gases sweeping the tubes in cross flow. The new experimental observations reported in the research program of the Babcock & Wilcox Company by Huge and Pierson are therefore of the utmost importance. Results of tests are reported for a large number of tube spacings of the commonly used staggered and in-line arrangements with different tube sizes, with a sufficient number of checks to assure their general accuracy. Special equipment was built and tested by Huge to investigate the influence of equipment size on convection and flow resistance and the results appear to confirm substantially the validity of the similarity principle. Before these new data could be used in practice, a great deal of analytical study has been necessary; this is the subject of the present paper. It was considered essential to satisfy the following major requirements: (a) Develop or select a method of correlation and of application of the original data to commercial equipment, for which conditions of size and operation may differ greatly from those of the experiments. The general relations developed from the principle of similarity, which have been used by Pierson and Huge in presenting their results, were selected for this purpose initially. (b) Examine the general relations for validity. These appear to be satisfactory except that a few uncertainties exist in details of application. (c) Study differences in characteristics from available sources from the viewpoint of causes and where necessary modify the original data consistently to reconcile such differences. (d) By fairing methods correct accidental errors of small magnitude. (e) Define the relation of the data to the whole problem or process and indicate the method of application to working needs in a sound general procedure. (f) Compare the over-all calculated results with results of reliable field tests of commercial equipment, as well as with experimental results of other investigators. These comparisons indicate that the new data are satisfactory with regard to both accuracy and utility. All of these phases are discussed at some length in this paper, and the results are summarized in the form of working relations and charts.