Nicolas Leonard Carnot

1994/02/01 Azkune Mendia, Iñaki - Elhuyar Fundazioa Iturria: Elhuyar aldizkaria

• Biografiak

This French physicist joined the famous family on June 1, 1796. His father, Lazare, stood out in the Government of the First Republic and with Napoleon I.

Nicolas Leonard Carnot, however, graduated in 1814 from the Paris Polytechnic School and was an Army engineer. That same year he dedicated himself to defending Paris, defending his father Antwerp. However, when Napoleon fell, his father had to go into exile and Carnot left the Army for not being able to ascend there. He began to study the distillation of gases and the characteristics of aromas.

In 1824 he wrote the book “On the Driving Force of Fire...”. Despite its good scientific level, until 1834 scientists discarded it. It defines work as the height at which weight has been lifted by weight.

Watt had invented the steam engine, but was concerned about the work that could be achieved from the thermal machine Carnot. In Carnot's time, the steam engine had a yield between 5 and 7 percent, that is, only 5% of the heat energy of the fuel was used to work and the remaining 95% was lost in the form of heat.

Carnot wanted to know to what extent the performance was improved and demonstrate that the optimum engine performance depended on the temperature difference. The perfume temperature in the steam engine _(T1) was the highest and the cold water (T2) the lowest. Most of the heat energy that could be transformed into work, being the perfect machine, could be expressed as follows:

T1-T2———T2

In this equation, temperatures _{T1 and T2 are absolute} and Kelvin made clear the concept of absolute temperatures a day later.

The conversion of heat into work and the conversion of work into heat was first studied quantitatively by Carnot. It can therefore be said that it is the generator of thermodynamics. His opinion on heat propagation was not correct, as it was based on Lavoisier's heat theory, but the results were correct.

The Carno equation shows that the maximum working quantity is the maximum and minimum temperature, and the intermediate temperatures are independent. The slow or rapid change in intermediate temperatures had nothing to do with it. The dependence of the two extreme points and the intermediate points is known in thermodynamics.

About ten years later G. H. Hess showed that this is true for the heat and reactions he has at his side.

Carnot would allow deducing the second law of thermodynamics. Carnot himself could clarify this law, but he died at the age of thirty-six in Paris, the victim of a cholera plague (August 24, 1832). Carnot's work was followed in Britain by Lord Kelvin and Rudolf Clausius in Germany. The latter revealed the second law of thermodynamics.

On the other hand, the name Carnot is often mentioned in a certain cycle of thermodynamics. Carnot's cycle is famous. This reversible thermodynamic cycle consists of two isothermal and two adiabatic transformations.