l6o CALORIFIC POWER OF FUELS 



HEAT OF WASTE GASES. 



The heat carried to the chimney by the waste gases is 

 from several sources: 



1. Sensible heat shown by the temperature. 



2. Heat of vaporization of the hygroscopic water and the 

 water formed from the hydrogen of the coal. 



3. Heat retained by the combustible gases or their heat of 

 combustion. 



4. Heat represented by soot or black of the smoke. 



I. SENSIBLE HEAT OF THE TEMPERATURE. 



The calculation of the water equivalent of the heat carried 

 to the chimney as sensible heat requires the volume, tem- 

 perature, composition, and specific heat of the constituents. 



The specific heats of the usual constituents of waste gases 

 are shown in Table VIII. The specific heats are supposed to 

 be under constant pressure, so as to avoid useless calculations. 

 The hydrocarbons or hydrogen will be omitted for the same 

 reason. Calling v t v f , v" y v'" the volumes in cubic metres 

 of the gases nitrogen, carbonic acid, carbonic oxide, and oxy- 

 gen, we find their respective weights, by multiplying these 

 volumes by the weight per cubic metre, 



1.25677 i. 96677' \.2$\v" I.43OZ/" 

 ~N~ "COT' CO ~0~ 



Multiplying these by the specific weights we obtain the value 

 in water, 



C = 1.2562; X 0.244+ 1.966^ X 0.217 + i.25iz>" X 0.245 + 

 I.430?/" X 0.217. 



The equivalent in water c multiplied by the temperature 

 on leaving the boiler gives calories, 



C = c X T. 



