The Compound Engine |
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120 pounds absolute 30 pounds amount of steam back pressure line ceiver clearance COMBINED DIAGRAM compound engine compressed cranks at 120 CROSS-COMPOUND RECEIVERS cubic foot curve cylinder condensation cylinder ratio diagram shown divide expansion line free expansion greater high pres high pressure cylinder high pressure diagram high pressure piston horse power horse-power initial pressure length load loop low pres low pressure cylinder low pressure diagram low pressure piston mean effective pressure mean pressure N. Y. FIG number of expansions one-quarter ordinate original volume pansion point of cut-off POSITION F pound of steam pounds boiler pressure pounds pressure quarter stroke ratio of expansion receiver pressure repre scale shown in Fig simple engine steam is expanded steam line steam per hour superheated Suppose sure cylinder surfaces TANDEM-COMPOUND RECEIVERS terminal pressure TOTAL EXPANSIONS total ratio triple expansion engine valve VOLS volume of steam VOLUMES 2 VOLUMES volumes at 30
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Page 20 - ... cylinders in series. The third principle permits an estimate to be made of the probable internal wastes of the series, and the probable total expenditure, of heat and of steam, and a solution of all problems of efficiency for the compound engine, of whatever type. The first step in the process is evidently the determination of the best ratio of expansion, under the assumed conditions of operation and for the given type of engine, for a single cylinder ; then the best ratio of expansion for the...
Page 35 - Receiver Space. — The space between the valve of the high-pressure cylinder and that of the low pressure cylinder, into which the steam exhausts from the high-pressure cylinder, should be from 1 to 1.5 times the capacity of the highpressure cylinder, when the cranks are set at an angle of from 120° to 90°. When the cranks are opposite or nearly so, this space may be very much reduced. The pressure in the receiver should never exceed half the boiler pressure, and is generally much lower than this....
Page 20 - ... may be economically carried in a single cylinder will vary somewhat with the initial temperature and pressure, and with the physical condition of the working fluid; but it may be taken as ordinarily not less than...
Page 35 - ... receiver, loaded by weight or spring to a pressure of 20 to 30 Ibs. per square inch; otherwise, owing to the large flat sides between the two cylinders, great risk of explosion would be run. This safety valve is usually of the same size and design as the cylinder escape valves. The receivers of three-crank engines need not be nearly so large, as the cranks are usually at angles of 120° ; in the case of triple compound engines with the MP leading the HP, a very small receiver will do.
Page 20 - Rankine suggests that the ratio of the cylinders be equal to the square root of the ratio of expansion. Thus if the steam has a total expansion of nine, the cylinder ratio would be three.* Mr. CE Emery deduces from the results of his experiments with US Revenue Steamers that the most economical ratio of expansion of steam in two-cylinder compound engines, where the pressure varies from 75 to 95 Ibs. absolute, is 22 -\- initial absolute pressure Ratio of expansion = — Triple-expansion Engines.
Page 1 - If you will consider that statement a little you will find that it means that the product of the volume and the pressure is constant.