Author: Frankling Institute

Publisher: Forgotten Books

Published: 2016-11-05

Total Pages: 478

ISBN-13: 9781334178429

Excerpt from Journal of the Franklin Institute of the State of Pennsylvania, for the Promotion of the Mechanic Arts, Vol. 69: Devoted to Mechanical and Physical Science, Civil Engineering, the Arts and Manufactures, and the Recording of American and Other Patent Inventions; January, 1860 The practical difficulty that arises by the adoption of short tubes, is the necessity of increasing the number to obtain that heating surface which the ship-owner expects to receive from the manufacturing engi neer, and which he is not inclined to lessen, although with the improved arrangement it may be more effective. In considering the question of diameter and length of tubes, there are two points to be noticed: first, the sectional area through the tubes being sufficient to receive and convey the expanded gases from the fur nace without retarding the same; and, secondly, reducing the length of tube to a minimum consistent with the heating surface required, and the number of tubes that can be conveniently introduced.' It is not our wish to lay down the law on a subject so full of dith culty, but we can safely indicate in what direction we have erred, and what course should be pursued to remedy those errors. An imperfect and sluggish combustion is the inevitable result of con traction in the sectional area through the tubes, and a waste of fuel is as inevitable where there is a deficiency of heating surface for a given rate and amount of combustion. Numerous cases occur in daily practice in which both the above errors are existing, and are simply the result of defective information in the designer. It is not unusual to find a difference of 25 per cent. In the areas of the chimneys of boilers of the same size and proportions; considering that the heated products of combustion gradually cool and contract as they leave the tubes, and that the frictional surface is reduced from about 13 to 1, there can be no doubt that the sectional area of the fun nel should be considerably less than that through the tubes; we find, however, frequent instances, where the chimney is as large, and even larger in sectional area than the tubes. Then who decides on the height of the chimney? Why, frequently even in large establishments the draughtsman who prepares the rig ging plans, so as to make it look well with his spars, &c. Thus often a boiler that requires an unusually high chimney has a low one. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.