Carnot chose the principle of steam engines as the subject of his study, because it was the cutting-edge technology at that time and a matter of great interest, but Clausius had another reason for starting his thermodynamics from the analysis of the Carnot cycle: it was still unknown in those days where the heat is gone that is not converted to work and the Carnot cycle independent of this problem could simplify the model of thermodynamics. The direct contact results in the expansion of the cold body, which can be regarded as the result of work.Īlthough Clausius inquired into the non-repetitious and non-periodic work later, he confined himself to the conversion of heat to work in the Carnot cycle in his paper of 1850.
If the non-repetitious and non-periodic work suffices, we can make two substances of different temperatures come in contact with each other. Strictly speaking, the third body between a warm body and a cold body is necessary only when heat engines must produce the repetitious and periodic work. The concept of work in thermodynamicsĪccording to Carnot and Clausius, a heat engine requires another condition to produce motive power besides a warm body and a cold body, namely what Carnot called agent, usually the water vapor, which is in contact with a warm body and a cold body alternately.Īs ａ transmission of heat may take place by conduction without producing any mechanical effect when ａ warm body is in contact with ａ cold one, if we wish to obtain the greatest possible amount of work from the passage of heat between two bodies, say of the temperatures t and τ, the matter must be so arranged that two substances of different temperatures shall never come in contact with each other. Clausius gained the final insight of Carnot into the reconciliation between two principles without reading the manuscript 18 years after his death and thus succeeded in discovering the second law of thermodynamics prior to Thomson.
After stating this principle in his treatise, Reflections on the Motive Power of Fire, published in 1824, he gave up the principle of the conservation of heat and admitted in his posthumous manuscript that part of heat could be converted into work. The “real fundamental principle of Carnot" is such that the production of motive power is due to the transportation of heat from a warm body to a cold body. On ａ nearer view of the case, we find that the new theory is opposed not to the real fundamental principle of Carnot, but to the additional principle “ no heat is lost," for it is quite possible that in the production of work both may take place at the same time ａ certain portion of heat may be consumed，and a further portion transmitted from ａ warm body to ａ cold one and both portions may stand in ａ certain definite relation to the quantity of work produced. In his paper of 1850, Clausius abandoned the principle of the conservation of heat and accepted Joule’s law as the first law of thermodynamics, while he also accepted Carnot’s principle as the second law of thermodynamics. Unlike Thomson, however, Clausius did not think Joule’s theory that heat can be converted into work contradicted Carnot’s theory that presupposed the conservation of heat. The reconciliation between Carnot and JouleĪlong with William Thomson (1st Baron Kelvin 1824 – 1907), Rudolf Julius Emmanuel Clausius (1822 – 1888) is one of the main founders of the modern thermodynamics who succeeded to Nicolas Léonard Sadi Carnot, the pioneer of this science. I will examine the range and limit of his theory that was already revealed at this early stage. Among them, the paper in 1850, On the Moving Force of Heat, and the Laws regarding the Nature of Heat itself which are deducible therefrom (Über die bewegende Kraft der Wärme: und die Gesetze, welche sich daraus für die Wärmelehre selbst ableiten lassen) is the starting point of his mechanical theory of heat. The thermodynamics of Clausius was gradually formulated in his papers of 1850, 1854, 18. The starting point of Clausius’s theory of heat Entropy as the sum of heat and disgregation The thermodynamic limit of Clausius’s approach Why can’t the equivalence value be negative of itself? What is the equivalence value of transformations? The theorem of the equivalence of transformations Mathematical formulation of Carnot’s principle The reconciliation between Carnot and Joule
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