Factory and industrial management . ion is substantiallycomplete, is to be expected from the nowwell-established fact that the specificheat of the v/orking substance increaseswith the temperature. The work done inthe gas engine cycle is mainly deter-mined by the rise of pressure which oc-curs on explosion; and in the same en-gine the area of the diagram with differ-ent mixtures is about proportional tothis rise, when corrected for the changein volume during combustion. If thespecific heat of the working substancewere constant, as is assumed in the air-cycle, the rise of temperature and there-f
Factory and industrial management . ion is substantiallycomplete, is to be expected from the nowwell-established fact that the specificheat of the v/orking substance increaseswith the temperature. The work done inthe gas engine cycle is mainly deter-mined by the rise of pressure which oc-curs on explosion; and in the same en-gine the area of the diagram with differ-ent mixtures is about proportional tothis rise, when corrected for the changein volume during combustion. If thespecific heat of the working substancewere constant, as is assumed in the air-cycle, the rise of temperature and there-fore of pressure at the explosion end ofthe diagram would be proportional tothe heat supply, and the efficiency wouldtherefore be constant. But the specific 597 59» THt, LNUlNhUKlISIir MAUAZ,n\ll. heat bcinr;-, in fact, greater at high tem-peratures, the rise of temperature or ofpressure on explosion increases in a lessratio than the heat supply, and the effi-ciency therefore diminishes as the supplyof heat is increased. >7C,0C0. e- ?400 eoo i;2oo 2fioo HiUx*.J^cmperaiure CerUjigrttJoLe>. FIGURE I. INTERNAL ENERGY CURVES. The ideal efficiency of a gas-engine,by which is meant the efficiency whichwould be attained if all-heat losses to thewalls were suppressed, and if combus-tion were complete and instantaneous atthe in-center, is easily calculated if theinternal energy of the working fluid isknown as a function of its cannot be said that we yet possess thisknowledge in any high degree of accu-racy, but enough is* known to enable anestimate to be formed of the effect ofstrength of mixture on efficiency. Fig-ure I shows the internal-energy curvescorresponding to the weakest and strong-est mixtures used in these ordinate of the curve is the quantityof heat in foot-pounds required to heata standard cubic foot of the burnt pro-ducts, at constant volume, from loo de-grees Cent, up to the temperature repre-sented by the abscissa. These curves
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Keywords: ., bookcentury1800, bookdecade1890, booksubj, booksubjectengineering
