1142 KB35 KB199920252016Hriberšek, MatijaKopač, JanezPušavec, FranciRech, JoëlŠajn, Viktorletnik:62številka:nr. 6str. 331-339ISSN:0039-2480COBISSID_HOST:14688027URN:URN:NBN:SI:doc-ZP4EXYYRenZveza strojnih inženirjev in tehnikov Slovenije etc.Strojniški vestnikinverzen problemkriogeno odrezavanjemerjenje temperaturenumerična simulacijatoplotna prestopnostukapljen dušikThe procedure of solving the inverse problem for determining surface heat transfer coefficient between liquefied nitrogen and inconel 718 workpiece in cryogenic machining|The determination of the cooling effect is important since the phase (liquid and gaseous) has a significant influence on the cooling effect, which indirectly influences the integrity of the machined surface after machining process. Therefore, this paper presents how the phase of liquefied nitrogen influences the surface heat transfer coefficient. The determination of the phase has been defined by resolving the inverse problem with conducted experiments and verified by the design of a numerical simulation. The experimental part includes the temperature measurement in the material (a plate of Inconel 718) at the time when the nozzle has moved across the plate, and the design of the numerical simulation. The results have shown that the surface heat transfer coefficient reaches the maximum value of 75000 W/(m 2 K) at the temperature difference (between liquefied nitrogen-Inconel 718 plate) of 196 K (liquid phase of the nitrogen). Steep value decrease for heat transfer coefficent (15000 W/(m 2 K)) at temperature difference 160 K (pure gaseous phase of the nitrogen) has been detectedCilj članka je prispevek k boljšem razumevanju vpliva ukapljenega dušika, ki se uporablja kot hladilo pri odrezavanju, na prestop toplote v Inconelu 718. V raziskavah je bila definirana toplotna prestopnost med ukapljenim dušikom in površino obdelovanca v odvisnosti od faze dušika. Uporabljeni material je bil Inconel 718, ki je visoko temperaturna zlitina niklja in kroma z izjemnimi mehanskimi in termičnimi lastnostmi in se uporablja v izdelkih z visoko dodano vrednostjo. Raziskava je bila izvedena na podlagi nepoznavanja natančnih vrednosti za toplotno prestopnost za omenjen kriogen fluid, saj so bile v dosedanjih raziskavah podane zgolj okvirne vrednostiTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Fakulteta za strojništvo