بررسي بعضي خواص مهم حرارتي مواد تغييرفازدهنده ارتقا داده شده با مواد نانوساختار

Investigation of Some Important Thermal Properties of Phase Change Materials Upgraded with Nanomaterials

ﯾﮑﯽ از ﮐﺎرﺑﺮدي ﺗﺮﯾﻦ روشﻫﺎ ﺑﺮاي ذﺧﯿﺮه ﺳﺎزي اﻧﺮژي ﮔﺮﻣﺎﯾﯽ، اﺳﺘﻔﺎده از ﻣﻮاد ﺗﻐﯿﯿﺮ ﻓﺎزدﻫﻨﺪه )PCMs( اﺳﺖ. در اﯾﻦ ﭘﮋوﻫﺶ، ﺗﺄﺛﯿﺮ اﻓﺰودن ﻣﻮاد ﻧﺎﻧﻮﺳﺎﺧﺘﺎر ﺑﺮ ﺑﺮﺧﯽ ﺧﻮاص ﻣﻬﻢ ﺗﺮﻣﻮﻓﯿﺰﯾﮑﯽ PCMs ﺷﺎﻣﻞ آﻧﺘﺎﻟﭙﯽ ذوب و ﺿﺮﯾﺐ ﻧﻔﻮذ ﺣﺮارﺗﯽ ﺑﺮرﺳﯽ ﺷﺪه اﺳﺖ. ﺑﺮاي اﯾﻦ ﻣﻨﻈﻮر از ﭘﺎراﻓﯿﻦ ﺑﻪ ﻋﻨﻮان PCMو از ﻧﺎﻧﻮذرات ﺳﯿﻠﯿﮑﺎ و اﮐﺴﯿﺪﻣﺲ، ﺑﺎ ﻫﺪف ارﺗﻘﺎي ﺧﻮاص ﺣﺮارﺗﯽ آن اﺳﺘﻔﺎده ﮔﺮدﯾﺪ. ﺑﺮاي ﺗﻮﻟﯿﺪ ﻧﻤﻮﻧﻪﻫﺎ، دﻗﯿﻖﺗﺮﯾﻦ روشﻫﺎ ﺑﻪﮐﺎر ﮔﺮﻓﺘﻪ ﺷﺪ و آﻧﺎﻟﯿﺰ رﯾﺰﺳﺎﺧﺘﺎرﺷﻨﺎﺳﯽ آن ﻫﺎ ﺑﺎ ﻣﯿﮑﺮوﺳﮑﻮپ اﻟﮑﺘﺮوﻧﯽ روﺑﺸﯽ ﻧﺸﺮ ﻣﯿﺪاﻧﯽ )FESEM( اﻧﺠﺎم ﺷﺪ. آﻧﺘﺎﻟﭙﯽ ذوب ﺑﺎ اﺳﺘﻔﺎده از دﺳﺘﮕﺎه ﮔﺮﻣﺎﺳﻨﺞ روﺑﺸﯽ ﺗﻔﺎﺿﻠﯽ )DSC( و ﺿﺮﯾﺐ ﻧﻔﻮذ ﺣﺮارﺗﯽ ﺑﺎ اﺳﺘﻔﺎده از دﺳﺘﮕﺎه ﻓﻼش ﻟﯿﺰر )LFA( اﻧﺪازه ﮔﯿﺮي ﺷﺪﻧﺪ. آزﻣﺎﯾﺶﻫﺎ ﺑﺎ آزﻣﻮن ﻓﺎﮐﺘﻮرﯾﻞ در ﻗﺎﻟﺐ ﻃﺮح ﮐﺎﻣﻼً ﺗﺼﺎدﻓﯽ ﺑﺎ ﺳﻪ ﻋﺎﻣﻞ اﺻﻠﯽ درﺻﺪ وزﻧﯽ ﻧﺎﻧﻮذره )در 3ﺳﻄﺢ(، ﻧﻮع ﻧﺎﻧﻮذره )در 2 ﺳﻄﺢ( و اﻧﺪازه ﻗﻄﺮ ﻣﺘﻮﺳﻂ ﻧﺎﻧﻮذره )در 3 ﺳﻄﺢ( و ﻧﯿﺰ ﭘﺎراﻓﯿﻦ ﺧﺎﻟﺺ ﺑﻪﻋﻨﻮان ﻧﻤﻮﻧﻪ ﺷﺎﻫﺪ، ﺑﺎ 3ﺗﮑﺮار اﻧﺠﺎم ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎندﻫﻨﺪه ﮐﺎﻫﺶ آﻧﺘﺎﻟﭙﯽ ذوب ﻧﺎﻧﻮﮐﺎﻣﭙﻮزﯾﺖ ﺑﺎ اﻓﺰاﯾﺶ درﺻﺪ وزﻧﯽ ﻧﺎﻧﻮذره اﺳﺖ، درﺣﺎﻟﯽ ﮐﻪ اﻧﺪازه ﻧﺎﻧﻮذره، ﺗﺄﺛﯿﺮ ﻣﻌﻨﺎداري ﺑﺮ آن ﻧﺪارد. ﻫﻤﭽﻨﯿﻦ ﺗﺄﺛﯿﺮ ﻋﻮاﻣﻞ اﻧﺪازه و ﻧﻮع ﻧﺎﻧﻮذره در ﺳﻄﺢ 1درﺻﺪ ﺑﺮ ﺿﺮﯾﺐ ﻧﻔﻮذ ﺣﺮارﺗﯽ Ne-PCMsﻣﻌﻨﯽدار ﺷﺪه اﺳﺖ. از آﻧﺠﺎ ﮐﻪ ﭘﺎراﻓﯿﻦ، ﻣﺎﻫﯿﺖ ﻏﯿﺮﻗﻄﺒﯽ دارد، ﻧﺎﻧﻮذره ﺳﯿﻠﯿﮑﺎ ﺑﺎ آن واﮐﻨﺶ ﺑﻬﺘﺮي داده اﺳﺖ و ﺧﻮاص ﺗﺮﻣﻮﻓﯿﺰﯾﮑﯽ ﻧﺎﻧﻮﮐﺎﻣﭙﻮزﯾﺖ ارﺗﻘﺎ داده ﺷﺪه ﺑﺎ ﻧﺎﻧﻮذره ﺳﯿﻠﯿﮑﺎ، ﺑﻪﻣﺮاﺗﺐ ﺑﻬﺘﺮ از اﮐﺴﯿﺪﻣﺲ ﻣﺸﺎﻫﺪه ﺷﺪه اﺳﺖ؛ ﻣﯽﺗﻮان ﻧﺘﯿﺠﻪ ﮔﺮﻓﺖ ﮐﻪ اﯾﻦ ﻧﺎﻧﻮذره ﺑﺮاي ﺑﻬﺒﻮد ﺧﻮاص ذﺧﯿﺮه ﺳﺎزي اﻧﺮژي ﺣﺮارﺗﯽ در PCMs ﻣﺆﺛﺮﺗﺮ اﺳﺖ.

One of the most practical methods for thermal energy storage is the use of phase change materials (PCMs). In this study, the effect of nanomaterial loading on some important thermophysical properties of PCMs including melting enthalpy and thermal diffusivity coefficient was investigated. Silica (SiO2) and copper oxide nanoparticles (CuO) were incorporated into Paraffin wax as a PCM to enhance its thermal properties. To produce the samples, the most accurate methods were used and their morphology was studied by field emission scanning electron microscopy (FESEM). Melting enthalpy and thermal diffusivity were measured by a differential scanning calorimeter (DSC) and a laser flash apparatus (LFA), respectively. The experiments were performed in a factorial arrangement in a completely randomized design with three main factors including the weight percentage of nanoparticles (three levels), the type of nanoparticle (two levels), and the size of the nanoparticles (three levels), and pure Paraffin wax as a control sample with three replications. The results showed that the melting enthalpy of the nanocomposite decreased with the increasing weight percentage of nanoparticles while the size of the nanoparticles displayed no significant effect. In addition, the size and type of nanoparticles affected thermal diffusivity coefficient of Ne-PCMs significantly (p<0.01). Since the enhancement of thermophysical properties of the nanocomposites containing silica nanoparticles was better than copper oxide, it can be concluded that this nanoparticle is more effective in improving the thermal energy storage properties of PCMs.