Irreversible evaporation of ammonia in vertical annular evaporators using helium as inert gas

Kouremenos, DA; Stegou-Sagia, A; Antonopoulos, KA

dc.contributor.author	Kouremenos, DA	en
dc.contributor.author	Stegou-Sagia, A	en
dc.contributor.author	Antonopoulos, KA	en
dc.date.accessioned	2014-03-01T02:47:55Z
dc.date.available	2014-03-01T02:47:55Z
dc.date.issued	1990	en
dc.identifier.issn	02725673	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/33436
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-0025558712&partnerID=40&md5=4141c0fd156c1af91d8623b9beeeea60	en
dc.subject.other	Evaporators	en
dc.subject.other	Mass Transfer	en
dc.subject.other	Mathematical Techniques--Finite Difference Method	en
dc.subject.other	Refrigerating Machinery--Absorption	en
dc.subject.other	Thermodynamics	en
dc.subject.other	Ammonia/Helium Mixture Flows	en
dc.subject.other	Inert Gas Absorption Refrigeration	en
dc.subject.other	Liquid Ammonia Flows	en
dc.subject.other	Second Law of Thermodynamics	en
dc.subject.other	Vertical Annular Evaporators	en
dc.subject.other	Ammonia	en
dc.title	Irreversible evaporation of ammonia in vertical annular evaporators using helium as inert gas	en
heal.type	conferenceItem	en
heal.publicationDate	1990	en
heal.abstract	The irreversible evaporation of ammonia in neutral gas absorption refrigeration units using helium as inert gas is calculated by a numerical algorithm. The physical situation considered is as follows: A thin annular film of liquid ammonia flows downwards on the interior surface of a vertical circular tube and evaporates within a downwards flowing gaseous mixture of helium and ammonia. The algorithm developed is based on a finite-difference solution of the momentum heat and mass transfer differential equations. Functions describing the thermodynamic properties of the ammonia/helium mixture are given. Attention is focussed on thermodynamic and second law aspects and especially in the entropy increase. Detailed information is presented including velocity, temperature, concentration, entropy, and enthalpy fields. The overall characteristics of the process are also calculated, i.e. the total heat exchanged and the total entropy increase. The predictions obtained showed that the ammonia/helium and the ammonia/hydrogen mixtures behave similarly and therefore helium can replace hydrogen in large inert gas absorption refrigeration units in order to avoid explosion hazards. The entropy increase is higher in the case of helium. The simulation method developed may be used in the design of evaporators for inert gas absorption refrigerators using helium as inert gas.	en
heal.publisher	Publ by ASME, New York, NY, United States	en
heal.journalName	American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD	en
dc.identifier.volume	151	en
dc.identifier.spage	15	en
dc.identifier.epage	24	en