20 KB198 KB18 KB200020242012Charvat, PavelKlimes, LubomirOstry, Milanštevilka:4letnik:46str. 335-338ISSN:1580-2949COBISSID:936362URN:URN:NBN:SI:doc-DKNNC0HQenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijeeffective heat capacity methodentalpijska metodaenthalpy methodmateriali s faznimi premenami (PCM)metoda učinkovite toplotne kapacitetephase change material (PCM)solar air collectorsončni kolektorChallenges in the computer modeling of phase change materials| Izzivi v računalniškem modeliranju materialov s fazno spremembo|Phase-change materials (PCMs) are a well-established category of materials with many possible applications, ranging from the stabilization of temperature to heat or cold storage. The main principle of PCMs is the utilization of the latent heat of a phase change for energy storage. Though many pure chemical elements can be used as PCMs, a PCM very often consists of a number of substances. The main reason for creating a PCM as a mixture of various substances is to achieve a desirable melting temperature for a particular application. However, these mixed PCMs require accurate and reliable methods for determining their physical properties, since for numerical modeling the thermal properties of materials and their proper determination represent a significant issue that considerably affects the accuracy and credibility of numerical simulations and their outcomes. The thermal properties of PCMs are usually obtained by differential scanning calorimetry (DSC), based on temperature and heat measurements of the investigated and reference materials. There are several approaches to modeling materials with phase changes. In this paper, the focus is on the enthalpy approach and the effective heat capacity method. Both techniques, which utilize the results from a particular DSC measurement, allow a treatment with the latent heat, and as a result the desired heat or cold storage may be effectively simulated. The presented methods were implemented using the results from DSC measurements in order to simulate a solar air collector with a PCM. The obtained results are presented and discussed. The paper also concerns the problems associated with the uncertainty of material properties and their influence on numerical simulationsMateriali s faznimi premenami (PCM) so uveljavljena kategorija materialov z mnogimi področji uporabe: od stabilizacije temperature do shranjevanja toplote ali hladu. Glavni princip PMS je uporaba latentne toplote pri fazni premeni za shranjevanje energije. Čeprav je mogoče uporabiti kot PCM mnoge čiste kemijske elemente, se pogosto uporablja mešanica različnih elementov. Glavni razlog za uporabo mešanice za PCM je zagotavljanje želene temperature tališča za določen namen. Vendar pa mešanica PCM-ov zahteva natančne in izvedljive metode za določanje fizikalnih lastnosti. Numerično modeliranje termičnih lastnosti materialov zahteva zanesljivo določene termične lastnosti, kar bistveno vpliva na natančnost in zanesljivost simulacij in njihovih rezultatov. Termične lastnosti PCM-materialov navadno določamo z DSC-metodo, ki temelji na merjenju temperature in toplote preiskovanega in referenčnega materiala. Obstaja več načinov, kako modelirati materiale s faznimi premenami. V tem članku je glavna pozornost posvečena entalpijskemu približku in metodi efektivne toplotne kapacitete. Obe tehniki, ki uporabljata rezultate DSC-meritev, omogočata uporabo latentne toplote, kar omogoča učinkovito simuliranje shranjevanja toplote ali hladu. Predstavljeni metodi sta bili uporabljeni z uporabo rezultatov iz DSC-meritev za simulacijo sončnega kolektorja s PCM-materiali. Predstavljeni so rezultati z diskusijo. Članek obravnava tudi problem nezanesljivosti podatkov o lastnostih materialovin njihov vpliv na numerično simulacijoTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije