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Physics Will these irreversible processes have anything to do with the fact that coal transformed into ashes can not be reversed in coal cooling? In their studies, Clausius sought to reconcile the universality of the First Law of Thermodynamics and the separation between reversible and irreversible processes. He postulated that: "Heat can never pass from a colder body to a body warmer without occurring while associated changes." All we know about the exchange of heat between two bodies of different temperature confirms this, as the heat everywhere manifest a tendency to equalize temperature differences and therefore to pass in the opposite direction, that is, the hotter body to the coldest. The previous postulate consists in what we now call the Second Law of Thermodynamics, version of Clausius. In practice, this assumption is not true, it would be possible to cool a room with a refrigerator, without the use of electricity, for example. But how equate this law? Let's start thinking about the purpose of a heat engine: converting a certain amount of heat into work. Well, so what? In fact, the second law does not invalidate the first, the only consideration is that the whole story has not been told. In practice, the thermal reservoir that appears on the Carnot Cycle may be, for example, the ambient atmosphere or large bodies of water, such as the initial and final states are the same fluid, the internal power may be considered constant (U = 0). Thus, the First Law of Thermodynamics can be rewritten as in Equation (1): Q = Q That Q is the heat absorbed in the process, given by the difference between the heat supplied by the hot source (Q ) and the heat rejected (Q ) to the cold source, which goes to the cold reservoir. Yield () a machine is defined as the ratio of the work done and the heat absorbed from the hot reservoir: The combination of Equations (1) and (2) leads to:
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Fizika Hoće li ovi procesi nepovratni ima veze s činjenicom da ugljen pretvara u pepeo ne može se ukinuti u uglja hlađenje? U svojim studijama, Clausius nastojala pomiriti univerzalnost prvi zakon termodinamike i odvajanje između reverzibilne i nepovratan proces. On je utvrdio da: "Toplina ne može proći od hladnijeg tijela na toplije tijelo ne javljaju, a povezane promjene." Sve što znamo o razmjeni topline između dva tijela različitih temperatura to potvrđuje, kao toplina svugdje manifestiraju tendenciju izjednačiti temperaturne razlike i stoga proći u suprotnom smjeru, to jest, toplije tijelo se hladnije. Prethodna postulatu sastoji se u tome što danas zovemo drugom zakonu termodinamike, verzija Clausius. U praksi, ova pretpostavka nije istina, to bi bilo moguće da se ohladi sobu s hladnjakom, bez uporabe električne energije, primjerice. No, kako se izjednačiti taj zakon? Počnimo razmišljati o svrsi topline motora: pretvoriti određenu količinu topline u rad. Pa, pa što? U stvari, drugi zakon ne izgubiti prvi, jedini motiv je da je cijela priča nije rekao. U praksi, termalna spremnik koji se pojavljuje na Carnotove može biti, primjerice, ambijentalno ozračje i velike vodene površine, kao što su početne i završne država su isti tekućine, unutarnje snage može se smatrati stalnim ( Dakle, prvi zakon termodinamike može prepisivati kao u jednadžbi (1): Q =Q q - Qf Da Q je toplina apsorbira u procesu, dao je razlika između topline isporučene do vrućeg izvora (Qq) i toplina odbijen (Qf) na hladnom izvoru, koji ide na hladnom spremniku. Prinos ( ) Od stroja definira se kao omjer obavljenog posla, a toplina apsorbira iz vrućeg spremnika: Kombinacija jednadžbi (1) i (2) dovodi do: