ENERGY LOSSES FOR MOTORS 583 



illustrations (Figs. 372, 373, 374, and 375). These losses 

 are also indicated in tabulated form as follows: 



ENERGY LOSSES IN STEAM PLANTS, PRODUCER GAS PLANTS AND 



GAS ENGINES, GASOLINE ENGINES, AND IN STEAM ELECTRIC 



POWER PLANTS 



Energy lost before reaching Steam ^?<J Gasoline Steam- 



the engine n?r rent engine, S2St plant> 



- nt ' per cent. per ' nt ' per cent 



In ashes ...................... 2.0 1.1 ........ 1.4 



In radiation and cooling ........ 4.6 18. 6 ........ 3.4 



In smoke.. 24.6 19.0 



PROBLEMS 



In solving the following problems we shall suppose that the energy 

 in coal is 3100 Cal. per Ib. and that bituminous coal costs $2 per 

 ton; that the energy in gasoline is 4785 Cal. per Ib. and it costs 15 

 cts. per gal. We know that 1 horse-power-hour of work equals 

 &40 Cal. of heat (Art. 655). 



1. How many pounds of coal will the steam engine (Fig. 372), 

 require to do 1 horse-power-hour of work? What would be cost of 

 fuel for 1 horse-power per day of eight hours? 



Solution: The engine delivers only 4.7 per cent, of the energy in 

 the form of useful work. One Ib. of coal contains 3100 Cal. of energy. 

 Therefore, 4.7 per cent, of 3100 Cal. or 145.7 Cal. is the amount of 

 energy delivered as work. But 1 horse-power of work equals 640 

 Cal. of heat. It will therefore require 640 -T- 145.7 or about 4.4 Ib. 

 of coal per horse -power-hour. 



Such a plant could be operated on bituminous coal costing $2 



