Vliv nanočástic TiO2 na přestup tepla při chlazení ostřikem kuželovou tryskou

Effects of titania nanoparticles on heat transfer performance of spray cooling with full cone nozzle

journal article in Web of Science

en

Spray cooling using aqueous titania nanofluids was studied. The temperatures of a testing plate under various spraying conditions were first measured; an inverse heat conduction technique was then applied to convert these measured temperatures into heat transfer coefficients (HTCs). It was found that the HTC increased logarithmically with the volume flux, but was decreased with the increase of the nanoparticle fraction. A correlation analysis was performed to quantify the HTC reduction caused by the increase of nanoparticles, and reconfirmed that the major cause for the HTC reduction was the difference in the impact (or impingement) behavior between solid nanoparticles and fluid droplets. A comparison study of the present findings with the previous published results was also performed and indicated that all results compared were consistent to each other based on the similar spray cooling conditions with different nanofluids or nozzles. The effects by using aquatic titania nanofluids instead of aquatic alumina nanofluids and by using full-cone nozzle instead of solid jet nozzle were specifically assessed and the associated rationales for the differences in these effects were given

Výzkum byl zaměřen na chlazení ostřikem kuželovou tryskou s použitím nanokapliny na bázi vody s nanočásticemi TiO2. Během chlazení byla měřena teplota tělesa pro několik různých podmínek ostřiku. Pro vyhodnocení součinitele přestupu tepla HTC byla použita inverzní úlohou vedení tepla. Výpočet ukázal růst HTC se zvyšujícím se průtokem, avšak se zvyšující se koncentrací nanočástic HTC klesalo. Ukázuje se, že hlavní příčinou poklesu HTC je rozdílnost v impaktním chování nanočástic a vodních kapek. Dále bylo provedeno porovnání s již dříve publikovanými daty; výsledky jsou konzistentní pro podobné podmínky ostřiku s různými druhy nanokaplin a trysek.

Spray cooling using aqueous titania nanofluids was studied. The temperatures of a testing plate under various spraying conditions were first measured; an inverse heat conduction technique was then applied to convert these measured temperatures into heat transfer coefficients (HTCs). It was found that the HTC increased logarithmically with the volume flux, but was decreased with the increase of the nanoparticle fraction. A correlation analysis was performed to quantify the HTC reduction caused by the increase of nanoparticles, and reconfirmed that the major cause for the HTC reduction was the difference in the impact (or impingement) behavior between solid nanoparticles and fluid droplets. A comparison study of the present findings with the previous published results was also performed and indicated that all results compared were consistent to each other based on the similar spray cooling conditions with different nanofluids or nozzles. The effects by using aquatic titania nanofluids instead of aquatic alumina nanofluids and by using full-cone nozzle instead of solid jet nozzle were specifically assessed and the associated rationales for the differences in these effects were given

kuželová tryska; součinitel přestupu tepla; nanokapalina; nanočástice; chlazení ostřikem; inverzní úloha vedení tepla

Full cone nozzle; Heat transfer coefficient; Impingement duration; Nanofluids; Nanoparticle; Spray cooling; Titania

2014

10.01.2014

Elsevier Ltd.

Spojené státy americké

1359-4311

62

1

20–27

8