0) 



a. 



2 3 











\ V 











*\ ^- 



. ise nt rop 



c 







-7 \^ 



^^^ 





4 





/ s e n f r o p i c \^ 



I 







Il~-- 











5 





Vo/uf 



<u 



(U 



a 



E 



const volume 



ressure 



Entropy 



Figure 7. — Idealized caloric engine cycle, thermodynamically similar to the 

 Stirling air engine cycle and to the modern gas turbine cycle. The toe (dotted) 

 of the p-v diagram can be approached in the gas turbine cycle, while the 

 constant volume expansion 4-5 is necessary in the reciprocating air engine 

 cycle because of limitations on maximum cylinder volume. 



That is, part of the energy supplied to the working 

 cylinder can be converted to work, and only part of 

 it, whether or not a regenerator is used. The portion 

 of energy that can be converted depends upon the 

 temperature at which heat is added to the working 

 medium (source temperature) and the temperature 

 at which heat is rejected to a condenser or the atmos- 

 phere by the working medium (receiver temperature) . 

 Under the operating conditions of the caloric engine 

 of the Ericsson, the maximum convertible portion of 

 heat to work was about one-third, and it is probable 

 that the actual conversion was more like one-sLxteenth. 



It is not surprising that Ericsson was snared by the 

 Second Law, which had only just been stated in 

 EngHsh by Lord Kelvin, who properly credited 

 Carnot and Clausius with the necessary ideas. It 

 was to take another generation of intellectual struggle 

 to get the two laws and their implications arranged 

 in an intelligible form.^^ 



The views and beliefs of many of Captain Ericsson's 

 American contemporaries have already been indi- 

 cated. An accurate appraisal of the ideas of other 

 practicing engineers in the United States cannot be 

 made because there existed in 1853 no association of 

 engineers competent to discuss the caloric engine. 

 However, the British Institution of Civil Engineers 

 devoted at least three of its weekly meetings in 1853 



' Keenan, op. cit. (footnote 50). 



to a "calm and deliberate discussion'" of the caloric 

 engine. ^^ 



Sir George Cayley, an elderly member of the 

 Institution who for half a century, off and on, had 

 been working on an air engine of his own design, 

 was not dismayed by the idea that perpetual motion 

 was involved in the caloric argument. A billiard ball 

 on a smooth surface would, he pointed out, roll on 

 forever if friction did not intervene. The escape of 

 heat in the caloric engine resembled friction. He 

 was confident that, if the practical difficulties such as 

 radiation losses and destructively high metal tempera- 

 tures could be overcome, the regenerative principle 

 was capable of reducing the consumption of fuel "to 

 an infinitesimal quantity." *^ 



At the other extreme, Mr. Hawksley, another 

 member, stated flatly that "the machine involved a 

 mechanical fallacy, as the regenerator produced no 

 mechanical efTect whatever." Air passed and re- 

 passed the regenerator as a result of the movement 

 of pistons; therefore the regenerator could not be 

 the cause of the pistons' movement. He conceded 

 that the engine would run, but, he said, "no part of 

 these results were, however, produced by the regener- 

 ator but, on the contrary, simply by the coal consumed 

 under the cylinder bottom. . . ." ^^ 



8^ Minutes of the Proceedings of Institution of Civil Engineers, 

 1853, vol. 12, p. 351. 

 " Ibid., pp. 334-335. 

 68 Ibid., pp. 349, 593. 



PAPER 20: JOHN ERICSSON AND THE AGE OF CALORIC 



55 



