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Kompozitni materiali za latentno shranjevanje energije
MARKOVIĆ, ANA (Author), Šebenik, Urška (Mentor) More about this mentor... This link opens in a new window

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Abstract
Problem velike porabe fosilnih goriv in elektrike za delovanje klimatskih naprav za ogrevanje prostora se lahko reši z nadomeščanjem z materiali za shranjevanje energije. Določeni materiali absorbirajo in sproščajo toplotno energijo kadar je to potrebno. Najugodnejši so materiali za latentno shranjevanje energije, saj se pri tem shrani toplota potrebna za spremembo temperature, kot tudi toplota potrebna za spremembo agregatnega stanja spojine, ki spreminja agregatno stanje/fazo (angl. Phase change materials - PCM). Temperatura tališča PCM spojine določa področje uporabe kompozitnega materiala, kar pomeni, da so za uporabo v stanovanjskih objektih najbolj ugodne PCM spojine, ki imajo temperaturo tališča v območju sobne temprature (25 ℃), kar so najpogosteje organske spojine, kot so na primer maščobne kisline ali parafinski voski. Omenjene spojine morajo biti ustrezno vgrajene v nosilni material, da bi učinkovitost bila čim višja in, da ne bi prišlo nastanka požara, saj so organske spojine vnetljive. Ustrezna metoda vgrajevanja je stabiliziranje PCM spojine v nosilni material pri povišani temperaturi, ki se potem ohladi pod temperaturo steklastega prehoda. Kompozitni materiali za latentno shranjevanje toplote imajo nizko toplotno prevodnost in se jim zaradi tega dodajajo dopanti na osnovi ogljika. Poleg izboljšane toplotne prevodnosti, dopanti zagotavljajo tudi boljšo stabilnost PCM spojine v nosilnem materialu. V diplomskem delu sta opisana oba primera uporabe dopantov v kompozitnih materialih za latentno shranjevanje energije. Obravnavane so predvsem morfologija, termične in mehanske lastnosti materialov, ter toplotna prevodnost. Rezultati pridobljeni iz strokovne literature so pokazali, da so kompozitni materiali za latentno shranjevanje energije stabilni po večjem številu ciklov segrevanja in ohlajanja, temperatura tališča in temperatura steklastega prehoda nosilnega materiala se ohranjata in sta neodvisna od koncentracije dopantov. Nosilni materiali so stabilni pri temperaturi tališča PCM spojine, kar pomeni, da jo lahko zadržijo, ko je v tekočem stanju in preprečijo puščanje. Količina shranjene latentne energije je dovolj visoka za praktično uporabo in znaša med 100 J/g in 200 J/g, odvisno od deleža posameznih komponent. V primeru mešanice 0,8 ut.% grafen oksida z 19,2 ut.% nosilnega materiala (mešanica lesnega prahu in poliuretana) in 1,2 ut.% grafen oksida z 18,8 ut.% nosilnega materiala se je toplotna prevodnost povečala osemkrat glede na čisto PCM spojino in čisti nosilni material.

Language:Slovenian
Keywords:shranjevanje latentne toplote, PCM spojine, kompozitni materiali s stabilizirano PCM spojino
Work type:Bachelor thesis/paper (mb11)
Tipology:2.11 - Undergraduate Thesis
Organization:FKKT - Faculty of Chemistry and Chemical Technology
Year:2020
COBISS.SI-ID:22000387 Link is opened in a new window
Views:320
Downloads:146
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Secondary language

Language:English
Title:Composite materials for latent energy storage
Abstract:
The problem of high fossil fuel and electricity consumption for operation of air conditioners and space heating can be solved by replacing them with the energy storage materials. Certain materials can absorb and release thermal energy when it is necessary. The most favourable are the materials, which can store the latent heat, as the heat required to change the temperature is stored, as well as the heat required to change the physical state of the phase change materials (PCM). The melting temperature of PCM determines the field of application of composite material, which means, that the PCMs which have melting temperature in the room temperature range (25℃), are the most suitable for use in the residential buildings. Most often these are paraffin waxes and fatty acids. These compounds must be properly incorporated into the carrier material/matrix in order to maximize efficiency and to prevent fire, as the organic compounds are flammable. A suitable method of incorporating is shape stabilization of PCM in the matrix at elevated temperature, then cool below the glass transition temperature. Composite materials for latent heat storage have low thermal conductivity. Therefore, carbon-based materials (dopants) are added. In addition to improve thermal conductivity, dopants also provide better stability of PCM in the matrix. In this thesis are described both examples of the use of carbon-based dopants in composite materials for latent heat storage. Morphology, thermal and mechanical properties and thermal conductivity of these materials are mainly discussed. According to the results obtained from the literature, composite materials for latent energy storage are stabile after a number of heating and cooling cycles. Melting point and glass transition temperature of the matrix are maintained and are independent of the concentration of dopants. The matrix is stable at the melting temperature of the PCM, which means, that it can retain the PCM, when it is in a liquid state and prevent leakage. The amount of stored latent energy is high enough for practical use and is between 100 J/g and 200 J/g, depending on the proportion of each component. In the case of mixture of 0,8 wt.% graphene oxide with 19,2 wt.% matrix (mixture of wood powder and polyurethane) and 1,2 wt.% graphene oxide with 18,8 wt.% matrix, the thermal conductivity increased eightfold compared to pure PCM and pure matrix.

Keywords:latent heat storage, phase change materials (PCM), composite materials with shape stabilized PCM

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