Nicolas Léonard Sadi Carnot

Nicolas Léonard Sadi Carnot ( born June 1, 1796 in Paris, † August 24, 1832 in Paris) was a French physicist and engineer, he founded with his theoretical consideration of the steam engine ( Carnot cycle ) a new branch of science, thermodynamics.

Sadi Carnot was the second son of the politician and scientist Lazare Nicolas Marguerite Carnot to the world. It was named after the Persian poet Sadi Shirazi. His father recognized early interest in mechanics and physics, and induced him to study the technical sciences. So Sadi began in 1812 at the École Polytechnique in Paris, but left this college in 1814 to become an engineer officer in the Corps of genius, a technical military force. Due to its republican conviction that he shared with his father, but he got there trouble even told him military service not very to. So he asked in 1819 to a provisional dismissal to himself entirely to science to give. These included chemistry, physics, mathematics, natural history and economics lectures to listen, visit industrial companies as well as to consider models of machines in museums, but also music and the works of Blaise Pascal, Molière and Jean de La Fontaine. He interrupted these activities are only once to visit his father, who spent his last years in exile in Magdeburg.

Publication

During his studies Carnot recognized advantages and perspective of the steam engine. As you improve, these machines only empirically, he considered it a matter of urgency, to consider in detail the " phenomenon of generation of movement by movement of heat ." The result was published in 1824 in the 43 -page script Réflexions sur la puissance du feu et sur ​​les motrice machines propres à cette puissance Développer ( Reflections on the motive power of fire and appropriate to the development of this engine ). This is the only font that was published during his lifetime Carnot. She found general approval, however, was soon out of print and has not been reprinted. It was not until 1890 appeared the English translation, and 1892 was Wilhelm Ostwald, a translation into German language out.

End of life

End of 1826 Carnot re-entered the military service and was promoted to captain on schedule. In 1828, he put his uniform from final to now to deal with all the sciences. He also did not participate in the July Revolution in 1830, though he had great expectations to democracy within them. When they finally did not meet, he turned back to his experiments. In June 1832 Carnot ill with scarlet fever and " brain fever ". He died shortly afterwards at the age of only 36 years, during a cholera epidemic.

Late reactions to the Carnot - font

Émile Clapeyron (1799-1864) attacked the first to the ideas contained in Carnot publication. He was content for " fruitful and einwurf free", but found with his 1834 versions also wrote little attention. Only after a quarter of a century, the situation changed: William Thomson, later Lord Kelvin suggested Carnot versions 1848 to its temperature scale. Rudolf Clausius referred in an article on thermodynamics in Poggendorff's Annals of Physics and Chemistry of 1850 expressly to Carnot's scientific performance, he spoke of "the most important ... [n ] belong here [n ] investigation ." It was surprising that neither Lord Kelvin Clausius still had the original script and knew only the Clapeyron processing. Only Wilhelm Ostwald translated the Carnot - writing for the first time into German. He noted that " ... it forms the essential content of what is called the second law of the mechanical theory of heat. As such, she has performed in the hands of Clausius and William Thomson to the most important results. "

Importance of Carnot font

Carnot stated in his reflections that they relate not only to steam engines, " ... but on every conceivable heat engine, which is also the material used, and the nature of acting on it." He noted that it was a recurring task during the performance, and gave it an ideal imaginary process that is now known in his honor as a Carnot cycle. With these two findings, he also laid the foundation for the development of various internal combustion engines, the Carnot cycle is to this day every design and analysis of periodically heat engines based. Carnot also stated that the process must be reversible, resulting in the development of the pump resulted.

Carnot's fundamental theorem states that wherever a temperature difference exists, moving force can be generated, since heat is always striving, from a hot to a cold state to move.

Carnot showed that the working machine is proportional to the amount of steam to the heat (more precisely, entropy) acts, which passes from the boiler to the condenser, that is high from the lower reservoir to the reservoir temperature. What is needed is a " inflow " and " outflow " of the heat (more precisely, the entropy ). The discharge can not take place at a lower temperature than the ambient temperature ( 298.15 K) normally. It follows that the maximum efficiency can not reach 1.

Carnot showed also that the efficiency of the larger temperature gradient also becomes larger. The result is that no heat engine can have a higher efficiency than those resulting from the " maximum moving force which results from the application of steam ." Each reversible engine is independent of the working substance, otherwise an appropriate combination of machines with different efficiencies could allow a perpetual motion machine of the second kind.

Inadequacy of the Carnot font

Carnot based his remarks on the theory that heat was a hypothetical, imponderable substance of unvarying quantity. This idea was at the time generally represented, Antoine Laurent de Lavoisier spoke of " Calorique ". Sir Benjamin Thompson and Sir Humphry Davy saw due to their friction experiments in heat but already a kind of movement. In 1850 Clausius introduced with an essay, the equivalence principle one, which leaves the idea of ​​a constant amount of heat. Julius Robert von Mayer mentioned it in 1842, James Prescott Joule, it was confirmed the following year experimental and Hermann von Helmholtz generalized it - regardless of Mayer - on all forms of energy. Clausius case has explicitly indicated that not the basic principle of Carnot is objectionable, but only the addition that no heat is lost.

Sadistic brother Lazare Hippolyte Carnot ( 1801-1888 ) published the second edition of the Carnot writing an annex with designs from the estate. These indicated that Sadi later diverged and now understood from his 1824 running view of heat as a form of energy. He determined the mechanical equivalent of heat even with 370 kpm / Calorie least 10 years before Mayer, which he had come very close to a universal law of energy conservation. Revolutionary reflections on authorship of the second law are still being discussed.