The steam engine indicator; Directions for the selection, care and use of the instrument and the analysis and computation of the diagram - Softcover
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 Excerpt: ...and cylinder condensation would be as great as though the load were larger. The loss per horse-power would be greater than the gain, and it is found to be more economical to cut off further in the stroke, as in Fig. 71, which, though it involves the loss of the area CAW in capability for expansion in the steam, increases the effective area of the diagram so much that the mean effective pressure is raised to 37.2 with no increase of the condensation and friction losses. If the cut-off were carried out furtht r the area gained becomes smaller as we get up into the corner at F, while the waste area CKM increases rapidly. Just as it is found advisable to increase the area of the diagram at the expanse of some free expansion at the end of the stroke, so it is found advisable to add to it by reducing compression, at the expense of not quite filling the clearance. Fig. 72 shows how by incurring a loss due to free expansion in the clearance proportional to the area PAD, the area of the diagram is increased' to 47.1, and though the volume Fig. 72. np to cut-off, including that proportion of the clearance inclosed in PAD would bear a greater proportion to the shaded area of the diagram than AB does to the area of Fig. 71, the steam actually required per horse-power will be less on account of the less-proportional loss from condensation and friction. Mr. F. H. Ball, of the Ball Engine Co., from whose argument the last three diagrams are copied, contends that "if in a given diagram any free expansion takes place at the terminal pressure, then compression should not rise to initial pressure, but the compression curve should be removed from the curve of full compression a sufficient distance, so that the useful work thereby added to the diagram shall be accompanied ...
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