ISBN: 1176731556 / ISBN-13: 9781176731554
An Introduction to Thermodynamics, for Engineering Students
by John Mills
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from ... Show 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. 1910 Excerpt: ... received. It then enters the room and is heated at constant pressure. If pa is 14.7 pounds absolute, pb is 14 times pa, 6a is to be zero degrees Fahrenheit, how much heat is abstracted from each pound of air while it is in the cooling room? Sketch the p-v plot for each cylinder and the 0-f Neglect the clearance. Assume that the Fia. 23 plot for the entire cycle cooling water reduces the tem-perature of the air to 95 Fah-renheit. Solution. pi = 14p = 206 pounds per square inch. Calling va equal to v, we find Vb and 6i by eq. (32) an- (19) as follows: 8b = PJ') " 0 = (14)029 (460) = 990. These values are plotted in Figure 25, which shows the work of the working cylinder W. These values are plotted in Figure 26, which shows the work done in the expansion cylinder E. The net input is then 3760 foot pounds per cubic foot of entering air. One pound of air at the admission temperature and pressure has a specific volume of Fig. 27 The work of the compressor per pound of air pumped is then (3760) (11.6) = 43,600 foot pounds. The B. t. u. equivalent of this work is 90 = 56 B.t.u. 778 The heat abstracted per pound by the room it is desired to refrigerate is V(Oi-0.) = 0.237(460-260) = 47.5 B. t. u. The cooling water must then remove the sum of these two amounts of heat or 103 B.t. u. As a check calculate the heat abstracted by the cooling water. It is evidently-9C) =0.237(990-655) = 103 B. t. u. The temperature-entropy plot is shewn in Figure 27. CHAPTER III WATER AND ITS SATURATED VAPOR 44. Phenomena of Vaporization. In accordance with the kinetic theory the molecules of a liquid are considered to be in motion in a manner similar to the molecules of a gas, except for the fact that the average free patlx which a molecule travels between impacts is ve...