86 THE THERMODYNAMICS OF THE MARINE OIL ENGINE. 



necessary to obtain and use the high-pressure air for injection; the other the low-pressure 

 engine which gives the same effective service results at a sacrifice of economy which varies 

 from 8 to 12 per cent. 



The Chairman : — If there is no further comment the Chair will call on Mr. Went- 

 worth to respond. 



Mr. WENTwroRTH : — In regard to what Mr. Howell said about the soot, I would like 

 to object to that point, because I do not think anything is impossible until it is tried out. 

 There is no doubt there would be a good deal of difificulty, as Mr. Howell said, but I do not 

 think it is insurmountable, because the fact that it is in commercial use to-day seems to 

 me to prove that it has possibilities. 



As far as what Mr. Haynie said, it seems to me that he has missed the point. If you 

 take the same high-pressure engine that you are using to-day you can increase your temper- 

 ature at that same pressure of injection of air and get the same effect of breaking up the 

 oil, with just half as much power put mto the air compressor, and the engine into which 

 the oil is injected will not show the least diminution of power, so that you have a clear gain 

 of just one-half of the compressor power. 



When I say "low compression," I refer particularly to the compression of the working 

 air in the cylinder, not the injection air. If you do reduce your pressure of compression in 

 your working cylinder, you can reduce your compression of injection air, that is, it is the 

 difference of pressure that breaks up the oil. For instance, we did run my experimental en- 

 gine until it was stopped. I confess that I made a mistake — I attempted to design not only 

 an engine but an air compressor. I bit off more than I could chew, without any question. 

 I had all kinds of trouble and the pressure would not hold up. We would start with the 

 air pressure away up, and run until we got out of breath, so to speak, but we could run with 

 a very low injection of air. The idea is to keep the compression of your injection air a 

 reasonable degree over the compression in the cylinder; but you must, to get the full benefit 

 of what I had in mind, feed the air in hotter or use hotter air for injection of the fuel. 



Mr. Haynie : — In using air, is it not a fact that the injection air is used largely for two 

 purposes? In the true Diesel or original Diesel, it was used as force to blow the oil into the 

 engine as well as to pulverize it ? 



Mr. Wentworth : — Yes. 



Mr. Haynie : — With the lower pressures that you refer to, it is not possible to always 

 follow that line, but you do have this value of disintegrating the particles, or breaking up 

 the particles of oil by impregnating it with air at some given pressure; just what the ratio 

 of that pressure is, is as yet an undetermined factor. I do not like to use trade names, but 

 you can take six or eight European engines built to-day which have obtained records in serv- 

 ice that are very enviable, and they all use a small volume of air injected with the oil at the 

 proper point, and while the oil is injected by pump pressure you break up the particles of oil 

 with air so that you get more complete combustion and eliminate the soot Mr. Howell 

 speaks of. Soot or carbon is the result of incomplete combustion, so if you break the oil 

 up into small particles or pulverize it by frequent blasts of air, you get complete combus- 

 tion if you get any combustion at all. 



