The Gas Turbine - Development and Engineering (el. knyga) (skaityta knyga) | knygos.lt

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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. 1914 ...would seem, therefore, that a gas-engine driving a centrifugal, and the centrifugal driving a water turbine, would give as good (if not a better) overall efficiency as the Humphrey pump-driven turbine, and that, unless the Humphrey pump has large practical advantages to atone for its lack in efficiency (a doubtful matter--it may be remarked that each unit at the Chingford installation carries 200 valves, all operated by springs), the scheme is altogether out of court. The final efficiency of the Humphrey pump water turbine plant may, however, be worked out, as a matter of abstract interest. The best impulse water turbines give from 78 to 84 per cent. efficiency (vide test results by Messrs. Escher, Wyss & Co.). Taking the gas producer efficiency at 84 per cent., and the higher value above quoted for the water turbine, and Dr. Unwin's test efficiency of 20-8 for the Humphrey pump, the final overall efficiency--ET = (20-8 X 84 X 84) per cent. = 14 7 per cent. Taking the calorific value of coal at 7,000 T.U. per lb., this gives a coal consumption of 1-375 lbs. of coal per brake horsepower per hour. If this result is compared with the figures of coal consumption for other prime movers (vide p. 203), it will be seen that, for the steam-engine the values lie between 1-6 and 1-1, and those for the gas-engine between 1-16 and 0-86. Or it may be compared to the test of a National Gas Engine at Manchester, October 23rd, 1900, when a coal consumption of 0-822 lb. was obtained (vide Clerk, "Gas Engine," Vol. II., p. 83). This shows sufficiently plainly the impracticability of the scheme from the point of view of economy. It may be argued, however, that, although on grounds of efficiency the application of the Humphrey pump for power transmission is not to...