Compressed air . Substituting the result just found in theabove equation, we have: Woi kdone=3 45/i i [(j-j — »] And this expression, when reduced bysing the value of n, becomes : Work done = /i <i [ (^) -i! . .(6) COMPRESSED AIR. 3934 This equation expresses the amount ofwork done in foot pounds to compressand deliver one cubic foot of free air,adiabatically, from a pressure pi to an-other pressure pi. By dividing by Vi the expression willrepresent the mean effective pressure(M. E. P.) per stroke, or, 45a[(^-^) (7) and therefore H. P. = Ji4^. M. E. .00436 M. E. P
Compressed air . Substituting the result just found in theabove equation, we have: Woi kdone=3 45/i i [(j-j — »] And this expression, when reduced bysing the value of n, becomes : Work done = /i <i [ (^) -i! . .(6) COMPRESSED AIR. 3934 This equation expresses the amount ofwork done in foot pounds to compressand deliver one cubic foot of free air,adiabatically, from a pressure pi to an-other pressure pi. By dividing by Vi the expression willrepresent the mean effective pressure(M. E. P.) per stroke, or, 45a[(^-^) (7) and therefore H. P. = Ji4^. M. E. .00436 M. E. P (8) /? — ^-^S pounds per square inch/•= — 14 75 + 90 = pounds persquare mch or H. P. = .00436 X M. E. P. - percubic foot of free air in single stagecompression. It was proved by F. A. Halsey that inproportionmg compound compressor cyl-inders, best results are obtained by divid-ing the work equally between the cylin-ders, or by proportioning them so thatmaximum saving in power is effected. /rtoS£?ACTt. c l—zy^e. \A a^c: i^z^TT^ Z- ^?z. <e £.f^ s 2 2 0 4 Fic. 2, -y- in which the pressures are reduced topounds per square I. Required the horse-power necessary tocompress one cubic foot of free air adia-batically to 90 pounds per square inchgauge pressure in a single-stage. (7) [(;-;/» (American Machinist, March 31. 1898).Letting Pi/iPz 3935 COMPRESSED AIR. ;Mr. Halsey found that for best propor-tioning /•i =r, = v^R (9) Now -6 X - = i r, = RP\ Pi _R If W/.^. = work in low pressure cylinderWi,p. = work in high pressure cylinder then from (6) W,.^. = /, V, (ri«-«-i) (10) W,.;,. = ^2 (^2--0 Ci) The total work done by the compressoris equal to the sum of the work done inthe low pressure and that done in thehigh pressure cylinder, or, W,.;.. + W,.^. = V, (-i-^^-!) -[-3-45/2^i.(-2°--i) (12 /l^l ?=/3^2 = 3-45/1^1 (-l»-I-f-2--l) = Pi v^ (R^+ R^^-2) = 3-45 Px ^1 (2 R°-—2) = zi(Rf-i«-i)
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectcompres, bookyear1896
