THE THERMODYNAMICS OF THE MARINE OIL ENGINE. 85 



DISCUSSION. 



The Chairman : — We are much indebted to Mr. Wentworth for the presentation of 

 his interesting paper, and we would Hke now to have a good discussion on it. (A pause.) 

 The Chairman would be very glad if the gentlemen discussing this paper quietly amongst 

 themselves would discuss it more publicly for the information of all. While this is not a 

 "hot air" engine, by any manner of means, we would all be pleased to have a full expres- 

 sion of views. The Chair feels sure that Mr. Wentworth is not so certain of everything 

 that he has said that he would not like to have some one criticize his statements. 



Mr. William N. Howell, Member: — I carried out a number of experiments for the 

 Lake Torpedo Company extending over about two years, and among other experiments we 

 had a boiler through which the exhaust gases from a Diesel engine were passed, and the 

 trouble with it was sooting up of the tubes. The Diesel engine is supposed to work when 

 conditions are favorable with no soot at all in the exhaust, but that only obtains when con- 

 ditions are entirely favorable. If there is any trouble with the fuel injection, which often 

 does occur, there is much soot, and, in all experiments of boilers connected with the ex- 

 haust of Diesel engines that I know of, this has been an insurmountable objection. Appara- 

 tus had to be provided to keep the tubes clean, and it was found to be practically impossible 

 to get good results from any kind of boiler connected with the exhaust. 



The Chairman : — The paper is still open for discussion. 



Mr. W. R. Haynie, Associate Member: — Mr. Wentworth refers to the variation in 

 the injection air pressure as having a bearing on the results of Diesel engines, and, fol- 

 lowing up Mr. Howell's suggestion of existing soot, I will say that the soot is really the re- 

 sult of incomplete combustion of the product used in the engine from which they want to util- 

 ize the heat contained therein. 



But, working back, after all, it is a question of combustion. Unless you can get com- 

 plete combustion of the oil or fuel (whether solid or liquid) which is injected into the en- 

 gine, you do not get all the heat contained in tlie oil. In the Diesel practice it has not been 

 proven by experience so far that you can do this by higher pressure injection of air. This air 

 does not mean any factor of energy at all, but a means of disintegrating the particles of oil, 

 so that the heat energy in the oil can be obtained by complete combustion. 



There are two questions — high or low pressure? If you are able to get greater bene- 

 fit from a lower pressure of air than the Diesel theory of high-pressure air for disintegra- 

 ting, or breaking up, or pulverizing the particles of oil to get the heat content from the oil 

 in expansive force, it is better. I do not mean this as a criticism of Mr. Wentworth's paper, 

 but there was a question in my mind which I could not get clear from my experience in this 

 line. 



I do know from experience and from tests that by a lower-compression pressure and 

 by eliminating high-pressure injection air you can simplify the mechanism in the prime 

 mover at a sacrifice in the volume of oil injected, or in the percentage of efficiency, any 

 way you want to term it, and yet get complete combustion. In other words, there are really 

 two general problems before the mechanical world to-day in this type of prime mover as ap- 

 phed to marine service, one being the high-pressure engine, with a number of mechanisms 



