Talk:Thomas Newcomen/Material from Wikipedia user Dr. Gabriel Gojon/A Genuine Steam Engine

A Genuine Steam Engine What Papin achieved within two years of receiving Leibniz's sketch of the Savery device, was a genuine direct action steam engine capable of being immediately applied to ships. Papin's engine successfully incorporated the dynamical innovations of 40 years of research that began with the project initiated by Huygens in Colbert's Academy. This achievement is fully documented in Papin's 1707 treatise, "New Method of Raising Water by the Force of Fire," published in Latin and French at Cassel. (This booklet is available today in select university libraries because someone in France had foresight to reprint 250 copies of it in 1914.) Papin's engine, shown in Figure 8, works as follows, with each step representing an innovation as a result of dynamical considerations. The engine is to be situated such that there is a constant flow of water into the pipe G. In this way, the water to be pumped enters the cylinder DD through H; the piston FF is then raised to the top of the cylinder by the weight of the water.

The copper vessel AA, which Papin calls the retort, is completely enclosed in a furnace, not shown. The furnace is designed to allow the fire to completely surround the retort, with precautions made to guarantee minimum loss of heat to the outside air.

The retort is supplied with a safety valve ab to allow a maximum controlled increase in steam pressure. The robinet, or spigot, E is opened, allowing the high-pressure steam to rush into the cylinder.

The opening L and the receptacle II are provided to allow insertion of hot irons in order to increase the violence of the steam, which is allowed to reach a controlled maximum with attention to the second safety valve ab.

The fulminating, expanding steam acts directly against the cold water through the mediation of the piston FF, arranged so that the surface of the piston encountering the steam remains hot, while the opposite surface remains relatively cold. The action of the steam on the piston forces the water out through H and up through the valve T. into the closed vessel NN. As NN fills with water, the air within NN is compressed.

The compression of the air in NN is allowed to increase until the robinet at the lower right of the vessel is opened, allowing the raised water to exit forcefully through pipe XX.

The resulting high-velocity jet of water encounters an improved paddlewheel, designed according to Papin's Fig. 2 (shown here in Figure 8). Papin's figure illustrates the advantages of adding blades to a mill wheel in order more completely to convert the energy of high velocity water into rotative motion. With this design, technology entered a new, dynamic universe. In a certain sense, it represents a transition, in that modern thermodynamic principles are applied to the ancient task of turning a water wheel. However, Papin intended immediately to apply his new engine to power the model paddlewheel boat, which he had constructed three years earlier.

In the preface to his 1707 treatise, Papin gives Leibniz full credit for providing the necessary impetus to advance his experiments. In particular, Papin cites two crucial junctures -the 1698 discussions on harnessing the direct force of steam versus mere atmospheric pressure, and the 1705 description of Savery's device that Leibniz's spies procured in London.

The quality of analysis in the treatise also shows the effect of Leibniz's firm theoretical commitment to "live force", combined with Papin's repeated experimental vindications of Leibniz's dynamics over the past 40 years. Papin concludes the first chapter, describing the furnace enclosing the retort:

5. The reason which obliges us to have such a great care to augment and conserve the heat [chaleur] is because it is the heat which makes all the moving force in this machine. Because otherwise in ordinary pumps it is animals, rivers, the wind or some other thing of this nature which employs their force in order to drive the piston in the pump and expel the water, here it is only the heated steam in the retort AA which travels with violence through the pipe ABB whenever the robinet E is opened, and goes to press the piston in the pump DD. And the force of this steam is even greater the more we give it a higher degree of heat. In chapter 3, Papin comments on the "means to augment the effect of the machine": 2. The augmentation of effect of which I have just spoken [that is, increasing the diameter of the pipes,and so on] is a little thing in comparison to that which could be obtained in augmenting the pressure in the retort AA: Because that of which I've spoken until now in order to impel [pousser] the water to 64 or 65 feet is equivalent to only two times the ordinary pressure of air: But it's certain that the pressure may be made much greater yet; with digesters or machines to cook bones, which weren't at all completely enclosed in their furnace, as is the retort M here, I sometimes achieved pressures equivalent to 11 times the pressure of air. Thus one may boldly say that the retort, being as well heated as it is and with the aid of hot irons enclosed in the pump DD, that pressures may be created much more than 6 times greater than that necessary to impel water to a height of 64 feet: and in such a case one man could create almost as much of an effect as 500 others who have only those inventions used up to the present. As for Savery's design, Papin describes in detail in chapter 5 how the Savery device was inferior to his own "in order that there be no misjudgment in the choice that will be made between Mr. Savery's machine and this one." First, Papin notes that since the retort M is "completely in the fire, it can be heated much more promptly and at less cost than the two vessels that Mr. Savery calls boillers." Second, Papin notes that his piston system ensures that the "steam loses none or very little of its force," compared to the condensation that occurs in the Savery device. Third, Papin describes his improvement that "allows the water to enter by its own weight into the pump DD, and not by suction" and writes, "without this correction, the inconveniences of which I've spoken about in this section would be enough to render the machine completely useless." Fourth, Papin notes the improvement of introducing hot irons to increase the "violence" of the steam. Then, "in order to incontestably prove that the piston FF is necessary to raise water to any considerable height," Papin reports that Savery's method completely failed to pump water "into air which had been a bit compressed.... Instead, a good effect is always created with the piston, even if the resistance of the compressed air in NN is 10 or 12 times greater than that which was impenetrable without the help of the piston."

Leibniz wasted no time in beginning the process of improving Papin's design. In his last published letter to Papin (Feb. 7, 1707), Leibniz not only suggested that the engine be made completely self-acting, and thus more appropriate to moving vehicles, but also proposed practical means of still further increasing the thermodynamic efficiency of the engine by the ingenious use of the so-called waste heat:

"I maintain that for stationary machines or for seagoing vessels, it will be difficult to make anything better along similar lines.... "I have a thought that perhaps will not displease you, which is to efficiently use the still-hot steam which leaves the pump when the piston is pushed up. Because it would be a great shame to lose it entirely. I imagine that in leaving it yet has much heat, and enough force to issue forth despite the outside air .... Then to make good use here of heat, otherwise superfluous, and at the same time of compressed air, in a manner which perhaps has never been used, I would make a sort of mantle or case ZZ around your vessel QN, partly filled with compressed air; and within this case I would let the steam enter in such a way that before it streams powerfully into the open air it would be between the case and the vessel. And while it warms this vessel it would as a result contribute towards the work of the compressed air contained therein. I believe that this will be a redoubling of the force .... and thus a mediocre vessel QN would make a much greater effect. Because it is already certain that heat gives as much force to ordinary air as does compression, and the same heat would give double or triple to compressed air .... The continual passage of hot steam would make this vessel extremely hot,almost as if it had been placed on a fire.

"I have always had the thought that a great effect could be made and much force placed in a small volume by means of air strongly compressed and then heated. This would be of great use for machines which must be portable.

"To say nothing of the superfluous heat of the furnace and the smoke which emerges from it which can be similarly useful among other ways by heating the water of the funnel G and of the tube H in order that the coldness of this water harms less of the heat in the pump D or in the vessel QN.... Furthermore, I have no doubt that you could, if you so desired, easily arrange that the robinets E and n are alternately open and closed by the machine without having to use a man for this."