Heat and heat-engines; A study of the principles which underlie the mechanical engineering of a power plant

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. 1899 edition. Excerpt: ...or isothermals equidistant in temperature divide the heat into equal parts. (6) If two bodies differ sufficiently in heat energy, a part of that excess of energy in the hotter body can be transformed into mechanical work by a proper heat-engine, and the remainder transferred to the cooler body. The test that all available heat energy has been transferred is that the entropy of the system has not been increased by a mere transfer as given in (1). If there has been such a transfer, the lost work is proportional to that increase in entropy. (7) The temperature condition of a medium which is to operate adiabatically in a heat-engine is a measure of its availability, since the lower temperature limit is fixed by that of the coldest available body. The area of the diagram increases as Tl increases, when T, is fixed by the temperature of water available for condensation. Hence: (8) Where a given heat-energy is under consideration, increase of entropy is concurrent with a loss of availability of that energy. (9) If the conditions of the preceding paragraph (197) be applied to one pound of steam, within very small variations of pressure, and consequently a small corresponding range of temperature, the height of the figure on thepv plane becomes also very small, or may differ from a rectangle by only an inappreciable quantity. If the symbol v denote the volume of the one pound of steam, the area on the pv diagram will be (/,--p,)v. The area on the Tp diagram will be 7",--T,)p, the temperatures belonging to the pressures of the pv diagram. Hence giving, when the relation of pressures and temperatures are given by a table, a method for calculating the value of 0. (10) Since the heat energy which disappears on making a liquid at a necessary temperature...