Heat transfer enhancement of nanofluids in a pulsating heat pipe for heat dissipation of LED lighting
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The effect of nanofluids on the heat transfer performance of a pulsating heat pipe has been experimentally investigated. Water-baseddiamond nanofluid and aluminium oxide (Al2O3) nanofluid were tested in the concentration range of 0.5-5%. The pulsating heat pipe was constructedusing clear Pyrex tubes of 1.85 mm in inner diameter in order to visualize the pulsating action. The total number of turns was eight each for heatedand cooled parts. The supply temperatures of heating water and cooling water were fixed at 80oC and 25oC respectively. The liquid charging ratio ofthe nanofluid was 50-70%. The test results showed that the case of 5% concentration of diamond nanofluid showed 18% increase in heat transfer ratecompared to pure water. The case of 0.5% concentration of Al2O3 nanofluid showed 24% increase in heat transfer rate compared to pure water. Butthe increase of Al2O3 nanofluid concentration up to 3% did not show further enhancement in heat transfer. It is also observed that the depositednanoparticles on the tube wall played a major role in enhanced evaporation of working fluid and this could be the reason for the enhancement of heattransfer by a nanofluid, not the enhanced thermal conductivity of the nanofluid.
Abstract
The effect of nanofluids on the heat transfer performance of a pulsating heat pipe has been experimentally investigated. Water-baseddiamond nanofluid and aluminium oxide (Al2O3) nanofluid were tested in the concentration range of 0.5-5%. The pulsating heat pipe was constructedusing clear Pyrex tubes of 1.85 mm in inner diameter in order to visualize the pulsating action. The total number of turns was eight each for heatedand cooled parts. The supply temperatures of heating water and cooling water were fixed at 80oC and 25oC respectively. The liquid charging ratio ofthe nanofluid was 50-70%. The test results showed that the case of 5% concentration of diamond nanofluid showed 18% increase in heat transfer ratecompared to pure water. The case of 0.5% concentration of Al2O3 nanofluid showed 24% increase in heat transfer rate compared to pure water. Butthe increase of Al2O3 nanofluid concentration up to 3% did not show further enhancement in heat transfer. It is also observed that the depositednanoparticles on the tube wall played a major role in enhanced evaporation of working fluid and this could be the reason for the enhancement of heattransfer by a nanofluid, not the enhanced thermal conductivity of the nanofluid.
참고문헌 (9)
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