Isentropic expansion and the three isentropic exponents of R152a

Kouremenos, DA; Floratos, OE; Kakatsios, XK; Fountis, G

dc.contributor.author	Kouremenos, DA	en
dc.contributor.author	Floratos, OE	en
dc.contributor.author	Kakatsios, XK	en
dc.contributor.author	Fountis, G	en
dc.date.accessioned	2014-03-01T01:48:36Z
dc.date.available	2014-03-01T01:48:36Z
dc.date.issued	1999	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/25530
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-0343005940&partnerID=40&md5=966a43c3b87ba94d171815ed5b33e0ef	en
dc.subject.other	Numerical methods	en
dc.subject.other	Pressure	en
dc.subject.other	Specific heat	en
dc.subject.other	Thermoanalysis	en
dc.subject.other	Velocity	en
dc.subject.other	Volumetric analysis	en
dc.subject.other	Constant pressure	en
dc.subject.other	Constant volume	en
dc.subject.other	Isentropic expansion	en
dc.subject.other	Isentropic exponents	en
dc.subject.other	Refrigerants	en
dc.title	Isentropic expansion and the three isentropic exponents of R152a	en
heal.type	journalArticle	en
heal.publicationDate	1999	en
heal.abstract	The isentropic change of an ideal gas is described by the well known relations pvk = const., Tv(k-1) = const. and p(1-k)Tk = const., where the exponent k is defined as the ratio of the constant pressure to the constant volume specific heat, k = Cp/Cy. The same relations can be used for real gases only if the differential isentropic changes under consideration are small. A better examination of the differential isentropic change shows that for p,v,T systems, there are three different isentropic exponents corresponding to each pair formed out of the variables p,v,T. These three exponents noted kT,p, kT,v, kp,v after the corresponding pair of variables used, are interconnected by one relation, and accordingly only two out of the three are independent. The analysis of the present paper shows the numerical values of these exponents as well as the isentropic expansion ratios for R152a in the vapor phase, presented in diagram form. It can be seen that the deviations of the three isentropic exponents relative to the conventional k = Cp/Cv values are considered and depend upon the initial pressure and the stage of the expansion. Additionally, the effect of the three isentropic exponents on the ideal gas relations describing the isentropic expansion ratios is examined, in order to develop simple yet more accurate relations without having to resort to the complex real gas state equations.	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	39	en
dc.identifier.spage	635	en
dc.identifier.epage	648	en