On the definition of entropy and temperature and on the energy interactions

Kouremenos, DA

dc.contributor.author	Kouremenos, DA	en
dc.date.accessioned	2014-03-01T02:48:41Z
dc.date.available	2014-03-01T02:48:41Z
dc.date.issued	1998	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/34015
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-0032311963&partnerID=40&md5=855ed2a37d312c3337170bbcf3d17bde	en
dc.subject.other	Differential equations	en
dc.subject.other	Energy transfer	en
dc.subject.other	Entropy	en
dc.subject.other	Mathematical transformations	en
dc.subject.other	Temperature	en
dc.subject.other	Vectors	en
dc.subject.other	Energy interactions	en
dc.subject.other	Thermodynamics	en
dc.title	On the definition of entropy and temperature and on the energy interactions	en
heal.type	conferenceItem	en
heal.publicationDate	1998	en
heal.abstract	The thermodynamic systems considered here are those that can be described by using only two macroscopic variables. For this purpose the specific volume v and the specific internal energy u are used while the pressure function p(u,v) is supposed to be known. It is shown that by a suitable mathematical transformation of variables, the pair (u,v) can be replaced by the pair of functions temperature T(u,v) and entropy s(u,v) that are defined simultaneously by a proposed generic system of differential equations without using the concept of heat. To show the authenticity of these definitions some solutions of this generic system of differential equations are given and in addition to, the special case of the perfect gas is obtained as one of the results. It is proposed to add to the conventional concepts of work and heat a third constitutive component, the throttling. With it the local efficiency η of a differential thermodynamic change can be defined. In addition this allows for the deduction of the relation (pdv+du)≥0 as a consequence. The heat-work energy interactions with a thermodynamic system are taking place mostly through an enclosing boundary wall. As these two different forms of energy flow cross the boundary wall, they undergo some transformation. As a result, the heat and work flow through the wall from/to the outer space to/from the system considered may change, although its algebraic sum, the total energy transferred, retains its initial value. Vector notation is used to facilitate the description of this transformation of energy crossing a boundary wall.	en
heal.publisher	ASME, Fairfield, NJ, United States	en
heal.journalName	American Society of Mechanical Engineers, Advanced Energy Systems Division (Publication) AES	en
dc.identifier.volume	38	en
dc.identifier.spage	221	en
dc.identifier.epage	233	en