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[quote user="Paul Milenkovic"] OK, I had a chance to search for Baldwin 60000 and came across the Altoona dynamometer test results. [quote]The locomotives of Chapelon, the French railway engineer, were marvels of efficiency and power by anyone's standards. A 4-8-0 type achieved 40 indicated horsepower per ton in the 1930s, a number perhaps never exceeded. His 4-8-4 constructed in 1946 (a rebuild of an unsuccessful 4-8-2 simple type) achieved efficiencies of 12% (early diesels probably operated at a lower efficiency than this) and a cylinder power output of 5,300 horsepower. In operation it could make 4,000 drawbar horsepower at 62.4 miles per hour from an engine weighing just 146 metric tons. Coal consumption at this speed and power level were 2.641 lbs/hour/horsepower and water consumption was 14.31 lbs/hour/horsepower. [/quote] As you know, there is HP (indicated HP or "in the cylinders" HP, brake HP, drawbar HP), and then there is coal (varying BTU content), and then there is water consumption per HP-hr (with steam pressure and superheat conditions varying). But a pound of water boiled somewhat around 300 PSI (gauge) pressure and 600 deg-F superheat temperature has enthalpy of about 1300 BTU/lb, water out of the feedwater heater at about 190 deg-F has about an enthalpy of 160 BTU/lb, water consumption of 14.31 lb/HP-hr corresponds to a heat rate of 14.31*(1300-160) = 16313 BTU/Hr, one HP-Hr is about 2550 BTU, so the thermodynamic efficiency indicated by the water consumption is 2550/16313 = 15.6 %. Baldwin 60000, also a 3-cylinder compound as the Chapelon A-1, reported somewhere in the high 14's, low 15's lb water/HP-hr in the Altoona tests across a suprisingly wide range of cutoffs, throttle settings, and speeds, giving thermodynamic efficiencies in the 13-14 range. However, a coal burn of 2.641 lb/hr is a BTU usage of 2.641*13,500 BTU/lb (again, that pesky question of what kind of coal?) = 35654 BTU/Hr, meaning the boiler efficiency on the A-1 was only 16313/35654 = 46% for an overall efficiency of 7.2 percent, about the same ballpark as Baldwin 60000.  Yes, the Baldwin 60000 used a higher boiler pressure of 340 PSI instead of 300 PSI in a Big Boy or whatever they used in France, but that modest increase in boiler pressure results in only modest gains. Maybe they use really low BTU coal in France, maybe there is a mixing of different HP values (IHP, BHP, DHP).  But I am beginning to wonder of there is a mix of lore and wishful thinking in some of the efficiency claims.  [/quote] This diagramm is from Baldwin 60000' site, <IMG src="http://www.cwrr.com/Lounge/Reference/baldwin/fig21.gif" mce_src="http://www.cwrr.com/Lounge/Reference/baldwin/fig21.gif"> ... as far as I understand, it just shows steam-locomotive boilers should not be pushed too hard. Cheers lars
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