Institution of Civil Engineers Minutes of proceedings of the Institution of Civil Engineers Volume 96

Minutes of proceedings of the Institution of Civil Engineers Volume 96

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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. 1889 Excerpt: ...heat at that temperature, the curve passing through the right-hand corners a b c of these parallelograms. It was convenient to set out the diagram on sectional paper, and so to arrange the scale that the area representing a heat-unit was an aliquot part of a square inch. Take, for example, 1 lb. of water at temperature T2. From the construction of the diagram the heat-units necessary to raise it from T2 to Tl were represented by the areas K + M enclosed between the vertical ordinates T2 and Tl; and the heat necessary to convert the 1 lb. of water at T, into steam at Tt was represented by the areas L + N. The area to the left of the ordinate T2, and bounded by the curve Tt T2 T3 and the base-line produced indefinitely to the left, represented the heat already in the 1 lb. of water at T2. Heat added might be represented by a series of vertical bands, such as Q2 Q0 Qv and each sufficiently narrow for it to be assumed, without sensible error, that the heat was all received at one temperature. When 1 lb. of steam was expanded in a cylinder from tempera-Mr. Willans. llr. Willans. pressure corresponding to T2, the work due from it was represented on the diagram by the areas K + L, or T2 Tt a e T2. At any period of the expansion, as, for instance, when the temperature had fallen to T0, the vertical line a f0 divided the horizontal line T0 T0, in the proportion in which the original lb. of steam was, at the temperature T0, divided into steam and water. The adiabatic curve could be constructed for any particular case in a few minutes, whereas by other methods the construction was rather difficult, involving considerable mathematical knowledge, or a most complicated graphical process. In setting out the adiabatic curve from this diagram, all that was necessary was to ...